THE  PITH  OF  ASTRONOMY 


UNIVERSITY  OF  CALIFORNIA 
AT  LOS  ANGELES 


TIIK    FORMATION    OF    COXSTKI.LATIOXS    BY    THE    ANCIENTS 


1  3  '33 


THE    PITH    OF   ASTRONOMY 

[  WIT  HO  UT  MA  THE  MA  TIGS} 

THE  LATEST  FACTS  AND  FIGURES  AS  DEVELOPED 
BY  THE  GIANT  TELESCOPES 


SAMUEL   G.  BAYNE 


WITH     ILLUSTRATIONS 


NK\V  YORK  AND  LONDON- 
HARPER   &    BROTHERS   PUBLISHERS 


Copyright,  18%,  by  HARPRR  &  BRorrrERS. 

All  rigktt  rtirrrrd. 


Engineering  & 
Mathematical 

Sciences 

Library 


-&5V 


.-' 


CONTENTS 


PA  UK 

INTRODUCTION v 

THE  SOLAU  SYSTEM 1 

THE  SUN 7 

MERCURY 17 

VENUS 19 

THE  EAUTII 22 

THE  MOON 29 

MARS 35 

JUPITER  .    .    .    .    - 39 

SATURN 44 

URANUS 49 

NEPTUNE 52 

COMETS 50 

ASTEROIDS  OR  PLANETOIDS G5 

SHOOTING-STARS 67 

THE  FIXED  STARS 75 

THE  CONSTELLATIONS 93 

NEBULAE 103 

MILKY  WAY 100 

DOUBLE  AND  MULTIPLE  STARS 109 

INTERESTING  ITEMS 114 


!04808 


ILLUSTKATIONS 


THE  FORMATION  OF  CONSTELLATIONS  BY 

THE  ANCIENTS Frontitpiece 

A  RING  THROWN  FROM  TBE  SUN  FORMING 

A  SEPARATE  PLANET Facing  payt  '  2 

ORBITS  AND  COMPARATIVE  SIZES  OF  THE 

PLANETS  IN  THE  SOLAR  SYSTEM  ...  "  4 

A  GREAT  SOLAR  SPOT  AS  SEEN  BY  LANG- 
LEY  "  8 

RELATIVE    SIZES  OF  THE  SUN   AND  PLANETS  "  12 

THK  RIM  OF  THE  MOON,  SHOWING  MARE 

CRISIUM "  30 

OBSERVATIONS  OF  MARS  SHOWING  ITS 

CHANGES "  36 

THE  PLANET  JUPITEU  AND  ITS  BELTS  .     .  "  40 

SATURN  AND  ITS  RINGS "  44 

THE  COMET  OF  1881,  AS  SEEN  THROUGH 

PROFESSOR  DRAPER'S  TELESCOPE,  JUNE  27  "  56 


vi  ILLUSTRATIONS 

STRUCTURE  Of  A  TEXAN  AKKOLITE.  .  .  fating  pa  ye  66 
A  SWARM  OF  METEORS  MEETING  THE  EARTH  "  68 

THE  CONSTELLATIONS  OK  ORION,  THK  TWINS, 

AND  THE  BULL "  76 

THK  CONSTELLATIONS  OF  THE  LION,  THE 

HERDSMAN,  AND  THK  GREAT  BEAR  .  .  "  94 
THE  GREAT  NEBULA  OF  ANDROMEDA  .  .  "  102 
THE  GREAT  NEBULA  ABOUT  THE  MULTIPLE 

STAR  ORIONIS,  IN  THE  CONSTELLATION 

OF  ORION "  104 

THE  CELEBRATED  CRAB  NEBULA  NEAR 

TAURI "  106 

THE  NEBULA  IN  THE  MILKY  WAY  ...  "  108 

YERKES  TELESCOPE "  1 1 4 


INTRODUCTION 

THE  large  modern  telescope,  celestial 
photography,  and  improved  astronomi- 
cal instruments  have  opened  the  field 
of  astronomy  to  such  an  extent  that 
the  ideas,  statements,  and  figures  of  a 
few  years  ago  are  no  longer  authentic. 
Happily  for  the  credit  of  astronomers, 
the  wonders  of  the  skies  have  been  un- 
derestimated, and  those  who  thought 
that  statements  that  had  been  pre- 
viously made  regarding  celestial  won- 
ders were  almost  beyond  credence  will 
be  pleased  to  find  that  they  were  not 
only  true,  but  that  in  reality  not  more 
than  half  the  truth  had  been  told. 


viii  INTRODUCTION 

The  writer  has  had  the  temerity  to 
compile  this  little  book  in  a  simple  and 
concise  form  for  the  use  of  those  who 
kno\v  but  little  or  nothing  of  astronomy, 
with  the  hope  that  it  may  lead  them 
further  to  investigate  this  most  delight- 
ful science.  No  mention  has  been 
made  of  signs,  Greek  letters  connected 
with  the  naming  of  stars,  or  the  mathe- 
matical features  usually  given  in  larger 
works  on  this  subject,  as  they  would 
only  tend  to  confuse  those  who  are 
seeking  for  elementary  knowledge  and 
to  learn  at  least  something  of  the  won- 
ders that  surround  us.  When  a  lay 
reader  has  finished  a  large  book  on 
astronomy  very  little  of  the  immense 
array  of  facts  and  figures  can  be  re- 
tained in  his  memory.  In  this  con- 
densed form  it  is  to  be  hoped  he  can 
remember  much  that  will  be  interesting 


•    ,  INTRODUCTION  ix 

and  useful,  should  he  go  no  further. 
It  is  also  intended  to  furnish  a  ready 
reference  for  those  who  desire  to  re- 
fresh their  memories  on  the  points  they 
have  known  but  now  forget,  and  to 
give  that  information  in  corrected  form, 
from  the  most  recent  observations  and 
calculations,  without  the  loss  of  time 
incurred  in  searching  larger  works  for 
simple  information.  For  those  who 
wish  to-  recognize  the  constellations 
and  celebrated  fixed  stars  at  sight — and 
what  pleasure  can  be  greater  than  rec- 
ognizing them,  as  we  do  old  friends, 
when  they  make  their  annual  reap- 
pearance in  the  sky,  if  it  be  not  that  of 
pointing  them  out  to  acquaintances, 
who  are  usually  eager  to  learn  their 
identity  and  something  of  their  his- 
tory ? — William  Peck's  Constellations, 
and  How  to  Find  Them,  is  perhaps  the 


X  INTRODUCTION 

best  and  easiest  guide  with  which  to 
find  the  stars ;  it  contains  but  a  few 
pages  of  read  ing -matter  and  twelve 
maps,  which  clearly  show  where  the 
stars  are  on  any  night  in  the  year. 

The  planets  wander,  as  their  name 
indicates,  or  rather  they  are  changing 
their  position  to  us  at  all  times,  and 
therefore  cannot  be  located  on  a  map, 
which  if  published  would  be  incorrect 
in  a  month  after  its  issue.  However, 
the  study  of  astronomy  has  of  late 
years  become  so  popular  that  most  of 
the  important  newspapers  employ  as- 
tronomers to  write  articles  on  the  ex- 
isting condition  of  the  heavens,  and 
those  articles  naturally  describe  the  lo- 
cation of  the  planets  then  in  sight,  so 
that  any  intelligent  inquirer  may  find 
them  with  comparative  ease.  It  may 
further  be  stated  that  a  powerful  opera- 


INTRODUCTION  xi 

glass  will  show  many  wonders  that  are 
lost  to  the  naked  eye,  and  that  the 
largest  telescope  that  can  be  mounted 
on  a  tripod  and  conveniently  moved 
out  of  the  owner's  residence  for  observ- 
ing is  a  3£  -  inch  lens ;  a  larger  size 
than  that  needs  a  permanent  founda- 
tion. It  is  an  axiom  in  sight-seeing  of 
all  kinds  that  when  fatigue  commences 
instruction  and  pleasure  end;  and  this 
will  be  verified  in  using  a  small  tele- 
scope that  needs  the  support  of  the 
hands  and  arms :  it  soon  tires  the,  ob- 
server. There  is  no  satisfactory  middle 
size  between  an  opera  -  glass  and  a  tele- 
scope mounted  on  a  tripod. 

The  figures  given  hereafter  represent 
averages  (where  there  is  a  difference  of 
opinion)  taken  from  the  highest  authori- 
ties, such  as  Sir  William  Herschel,  Pro- 
fessor Young,  of  Princeton,  Sir  Robert 


xii  INTRODUCTION 

Ball,  Professor  Langley,  Camille  Flam- 
marion,  Professor  Lockyer,  W.  H.  War- 
ren, Garrett  P.  Serviss,  and  many  others. 
The  estimates,  where  it  is  practical, 
are  given  in  round  numbers,  for  the 
purpose  of  enabling  the  reader  to  re- 
member them. 

In  beginning  the  order  of  chapters 
it  will  perhaps  be  best  to  commence  at 
home,  and  our  local  solar  system  will 
be  taken  up  first  by  a  description  of 
its  members,  starting  with  the  centre, 
our  sun,  and  running  out  to  the  fron- 
tier planet,  Neptune,  which  is  "  one  of 
the  family,"  although  it  is  more  than 
two  thousand  seven  hundred  millions  of 
miles  from  the  earth. 


THE  PITH  OF  ASTRONOMY 


THE  SOLAR  SYSTEM 

"That  very  law  which  moulds  a  tear, 
And  bids  it  trickle  from  its  source, 
That  law  preserves  the  earth  a  sphere, 
And  guides  the  planets  in  their  course." 

THE  natural  division  of  the  heavens 
most  interesting  to  the  inhabitants  of 
the  earth  resolves  itself  into  two  great 
parts — namely,  the  solar  system,  consist- 
ing of  the  sun  with  the  eight  planets 
which  revolve  round  it,  and  the  great 
suns  or  fixed  stars  which  shine  in  space 
at  immense  distances  from  the  earth. 

The  solar  group  and  its  planets  in- 
terest us  most  because  we  live  within 
its  confines,  and  our  earth  is  a  part  of 


2  THE   PITH   OF   ASTRONOMY 

the  system  which  enables  us  to  observe 
closely  and  easily  determine  the  dimen- 
sions, distances,  composition,  color,  and 
weight  of  our  neighbors  ;  while  the  stars 
are  so  far  from  us  that  a  large  portion 
of  our  information  regarding  them  is  to 
some  extent  speculative. 

The  sun  is  the  centre  of  the  solar 
system.  Eight  planets  revolve  around 
it — viz.,  Mercury,  Venus,  Earth,  Mars, 
Jupiter,  Saturn,  Uranus,  and  Neptune,  in 
the  order  named — and  are  held  in  their 
orbits  by  its  powerful  attraction.  The 
sun  is  a  fixed  star,  of  a  low  magnitude 
as  compared  with  the  giants  of  space. 
The  word  planet  means  a  wanderer,  and 
these  bodies  appear  to  wander  through 
the  skies,  changing  their  positions  daih7 ; 
while  a  fixed  star  does  not  move — per- 
ceptibly, at  least — in  a  hundred  years. 

The  planets  may  be  easily  known 


THE    SOLAE    SYSTEM 


from  stars  by  the  fact  that,  with  the 
exception  of  Uranus  and  Neptune  (re- 
volving so  far  out  in  their  orbits  that 
they  cannot  be  seen  by  the  naked  eye), 
they  are  larger  to  our  sight  than  the 
stars,  and  shine  with  a  steady  flame,  like 
a  lamp,  while  the  stars  twinkle,  as  a 
bright  point  of  light.  Those  who  have 
telescopes  may  readily  see  the  differ- 
ence ;  a  planet  will  show  a  distinct  disk, 
while  the  most  powerful  instrument  can 
only  make  the  star  point  brighter  and 
more  brilliant.  The  cause  of  this  is 
that  the  glass  entirely  fails  to  visibly 
magnify  at  such  immense  distances. 

The  moon  is  a  sort  of  grandchild,  viz., 
a  satellite  of  a  satellite — that  is  to  say, 
it  revolves  round  the  earth  while  the 
earth  is  revolving  round  the  sun.  And, 
for  that  part,  there  is  yet  another  step 
to  take  in  this  direction,  for  undoubted- 


4  THE   PITH    OF   ASTRONOMY 

ly  the  sun  itself,  with  its  entire  system 
of  followers,  is  attracted  towards  a 
giant  sun,  compared  with  which  our 
little  one  is  very  small  indeed.  Most 
of  the  other  planets  have  moons  revolv- 
ing round  them,  which  will  be  described 
in  the  proper  place.  It  may  be  men- 
tioned here  that  the  four  planets  near- 
est the  sun — namely,  Mercury,  Yenus, 
the  earth,  and  Mars — are  the  smallest 
and  densest,  and  each  turns  on  its  axis 
in  about  the  same  time,  while  the  four 
outside  giant  planets — Jupiter,  Saturn, 
Uranus,  and  Neptune — rotate  in  about 
ten  hours,  and  are  the  planets  of  the 
least  density.  The  first  four  are  known 
as  the  "  interior  planets,"  and  the  latter 
are  called  the  "  exterior  planets." 

An  immense  group  of  comets  must 
be  included  in  any  description  of  the 
solar  system,  no  matter  how  brief. 


ORBITS    AND    COMPARATIVE    SIZES    OF    THE    PLANETS    IN 
THE    SOLAR    SYSTEM 


THE    SOLAE    SYSTEM  5 

These  comets  describe  ellipses  in  their 
courses,  and  turn  on  the  sun  close  to 
that  orb,  then  run  out  into  space,  to 
return  again  in  what  is  called  their 
period — that  is,  the  term  of  years  that 
is  consumed  in  completing  their  orbit. 
Some  of  them  (notably  llalley's  comet) 
sail  out  far  beyond  Neptune,  and  as 
that  would  make  a  trip  of  six  thousand 
millions  of  miles  out  and  return,  it  is 
apparent  that  long  intervals  of  time 
must  take  place  between  their  appear- 
ances to  us  of  the  earth.  In  the  vast 
distance  between  the  orbits  of  Mars 
and  Jupiter  is  found  a  great  number 
of  asteroids,  as  they  are  called.  These 
also  revolve  round  the  sun,  as  do  the 
larger  planets,  but  they  are  so  small  by 
comparison  that  a  more  detailed  de- 
scription of  them  will  be  deferred  till 
later. 


6  THE   PITH    OF   ASTRONOMY 

Allied  closely  to  these,  but  still  small- 
er, are  the  meteoric  stones,  which  are 
scattered  through  the  skies,  and  rush 
round  the  sun  in  shoals,  from  the  size 
of  a  walnut  to  that  of  a  house.  All  of 
these  members  are  the  component  parts 
of  our  system,  running  in  size  from  the 
giant  planet  Jupiter,  almost  1300  times 
larger  than  our  earth,  down  to  stones 
not  as  large  as  oranges;  yet  all  these 
bodies  have  orbits,  composition,  and 
speed  differing  from  each  other,  but 
each  holding  its  proper  place  in  the 
solar  system  which  we  call  our  own. 


THE  SUN 

THE  diameter  of  the  sun  is  866,000 
miles. 

Its  mean  distance  from  the  earth  is 
93,000,000  miles. 

Its  volume,  or  bulk,  is  1,300,000  times 
more  than  the  earth. 

Its  mean  density  is  one-fourth  that 
of  our  earth,  or  about  the  consistency 
of  a  thick  fluid. 

It  revolves  on  its  axis  in  about  25 
days. 

Its  mass — that  is,  the  quantity  of 
matter  in  it — is  more  than  800  times 
greater  than  all  the  planets  combined. 

The  centre  of  gravity  of  the  whole 


8  THE    PITH    OF    ASTRONOMY 

solar  system  lies  within  the  body  of 
the  sun  when  Jupiter  and  Saturn  are 
not  on  one  side  of  it. 

The  force  of  gravity  at  the  sun's 
surface  is  28  times  greater  than  the 
gravity  on  the  earth.  A  man  weigh- 
ing 217  pounds  here  would  weigh 
over  three  tons  on  the  sun,  and  his 
own  weight  would  flatten  and  kill 
him. 

Light  travels  at  the  rate  of  186,000 
miles  per  second,  and  reaches  us  from 
the  sun  in  eight  minutes.  The  light 
from  the  sun  is  150  times  as  great  as 
that  of  the  lime  cylinder  of  the  calcium 
light,  and  it  makes  all  other  lights  black, 
by  comparison.  "With  modern  astro- 
nomical appliances  the  weight,  size,  and 
distance  of  the  sun  are  now  determined, 
and  with  the  aid  of  the  spectroscope 
scientists  tell  us  the  composition  of  the 


A   GREAT   SOLAR   SPOT 
(As  seen  by  Langley.) 


sun,  as  well  as  of  many  of  the  fixed 
stars  that  surround  us. 

The  sun  is  believed  to  be  a  mass  of 
intensely  heated  matter  in  the  gaseous 
state,  consisting  of  both  the  permanent 
gases,  like  hydrogen,  and  of  metallic 
vapors  powerfully  compressed  by  its 
own  gravity ;  this  compression  causes 
it  to  contract,  and  the  contraction, 
which  amounts  to  ten  inches  daily,  pro- 
duces the  intense  radiation  that  warms 
and  supplies  the  solar  system  with  en- 
ergy. If  we  take  the  sun's  diameter 
into  our  reckoning,  we  find  that  it  may 
require  millions  of  years  to  perceptibly 
affect  this  vast  globe  and  reduce  its  life- 
giving  influence  to  a  point  where  hu- 
manity will  freeze  to  death ;  but,  after 
all,  it  is  only  a  question  of  time,  as  the 
day  will  come  when  it  will  be  reduced 
to  a  dark  cinder,  and  travel  through 


10  THE    PITH    OF    ASTRONOMY 

space  as  dead  and  cold  as  the  moon  is  to- 
day. It  will  then  roam  through  the 
skies  until  perhaps  it  comes  into  colli- 
sion with  another  body,  when  both  will 
turn  into  a  nebula  of  floating  gas,  thus 
forming  the  nucleus  of  a  new  world, 
which  may  be  a  home  for  new  men  and 
new  things.  The  sun,  like  all  natural 
objects,  must  pass  through  the  regular 
stages  of  birth,  vigor,  decay,  and  death. 

The  heat  radiated  by  the  sun  defies 
all  human  conception.  It  is  a  gigantic 
furnace,  of  such  magnitude  that  com- 
parisons between  it  and  what  we  know 
of  heat  are  futile. 

A  few  of  these  may  interest  the  read- 
er. If  all  the  coal-fields  on  the  earth 
were  ignited  and  consumed  in  a  fire, 
they  would  not  supply  the  heat  emitted 
by  the  sun  for  the  tenth  part  of  a 
second. 


THE    SUN  11 

If  the  earth  were  to  fall  into  the  sun 
it  would  melt  and  evaporate  on  arriving 
there,  like  a  flake  of  sno\v. 

At  the  distance  of  93,000,000  miles, 
were  it  not  for  the  atmosphere  that  pro- 
tects the  earth  from  the  sun's  rays,  they 
would  melt  a  crust  of  ice  enveloping 
the  earth  100  feet  in  depth  in  a  year, 
and  would  cause  aJl  the  oceans  to  boil 
in  a  like  period. 

The  sun's  heat  at  its  surface  would 
also  boil  in  an  hour  seven  hundred  thou- 
sand millions  of  cubic  miles  of  water  at 
the  temperature  of  melting  ice ;  and  yet 
more  than  99  per  cent,  of  all  this  heat  is 
wasted,  not  having  touched  any  of  the 
planets  on  its  way.  Estimating  the  to- 
tal radiation  of  the  sun  at  two  thousand 
millions,  the  earth  receives  but  one  part 
of  this.  The  noise  of  the  terrific  dis- 
turbance on  the  sun  is  of  such  power 


12  THE   PITH   OF   ASTRONOMY 

that  it  alone  would  kill  a  man  were  he 
placed  within  5000  miles  from  its  rim. 
The  sun  has  a  continuous  Solution  of 
heat  equivalent  to  10,000  horse-power 
on  every  square  foot  of  its  surface.  A 
procession  of  icebergs  sent  against  the 
sun  would  be  melted  at  the  rate  of 
300,000,000  cubic  miles  of  solid  ice  per 
second. 

If  it  were  possible  to  have  started  an 
express  -  train  for  the  sun  in  1635,  it 
would  not  be  due  there  till  now,  and  a 
single  ticket  for  the  trip  would  have 
cost  $3,000,000.  If  a  small  community 
had  started  on  the  train,  the  seventh 
generation  only  would  reach  its  desti- 
nation. 

The  rays  of  heat  from  the  sun  on 
their  way  to  the  earth  pass  through  a 
practical  vacuum  which  has  a  tempera- 
ture of  300  or  400  degrees  below  zero ; 


RELATIVE    SIZES    OF   THE    SrX    AND    PLANETS 


THE    SUN  13 

they  pass  through  this  temperature  and 
have  apparently  no  effect  until  they 
meet  some  object,  like  the  earth,  capa- 
ble of  being  warmed  by  them. 

The  sun  has  prodigious  activity  in  its 
spots.  These  spots  are  sometimes  50,000 
miles  in  diameter,  and  it  is  by  observ- 
ing them  disappear  and  return  to  our 
sight  by  rotation  that  the  time  of  the 
sun's  rotation  has  been  determined. 

In  1858  a  spot  of  over  1073000  miles 
in  diameter  was  clearly  seen.  These 
spots  are  enormous  vents  for  the  tem- 
pests of  flame  that  sweep  out  of  and 
down  into  the  sun. 

An  up  rush  and  down  rush  at  their 
sides  have  been  measured  at  20  miles  a 
second ;  a  side  rush  or  whirl  at  120 
miles  a  second.  These  tempests  rage 
from  days  to  months  at  a  time,  and  as 
they  cease  the  advancing  sides  of  the 


14  THE   PITH    OF   ASTRONOMY 

spots  approach  each  other  at  the  rate 
of  20,000  miles  an  hour ;  they  strike  to- 
gether, and  the  rising  spray  of  fire  leaps 
thousands  of  miles  into  space ;  it  falls 
again  into  the  incandescent  surge,  and 
rolls  over  the  Himalayas  of  fire  as  the 
sea  over  the  pebbles  on  its  beach.  If 
ships  were  built  as  large  as  the  whole 
earth,  in  such  gigantic  tempests  they 
would  be  tossed  like  corks  in  an  ocean 
storm. 

The  incandescent  gases  which  are 
seen  on  the  surface  of  the  sun  some- 
times rise  as  high  as  250,000  miles; 
they  shoot  out  to  these  great  distances 
often  at  the  rate  of  several  hundred 
miles  per  second. 

The  sun  is  our  very  life-blood ;  with- 
out it  we  could  not  live  an  instant.  It 
directly  supplies  us  with  light,  heat, 
and  other  forms  of  energy,  and  indirect- 


THE   SUN  15 

ly  with  food,  clothing,  and  everything 
else  we  use.  This  provident  worker 
has  stored  coal,  petroleum,  and  natural 
gas  for  us  in  the  past  ages,  thus  giving 
us  an  inexhaustible  reservoir  of  power 
and  light.  It  furnishes  us  with  wood, 
and  lifts  the  waters  to  the  hills,  so  that 
in  their  passage  to  the  sea  man  may  be 
enabled  to  harness  them  for  his  use  in 
producing  the  necessaries  of  life. 

It  is  the  constant  alternation  of  evap- 
oration and  condensation  that  keeps 
all  the  waters  of  the  earth  in  a  state  of 
purity,  making  them  fit  for  us  to  drink, 
and  preventing  the  oceans  from  becom- 
ing stagnant.  The  salt  breezes  that 
sweep  over  the  storm-tossed  seas  purify 
the  air,  and  so  on,  ad  infinitum. 

We  journey  through  a  frigid  space, 
but  we  live,  as  it  were,  in  a  conservatory 
in  the  midst  of  perpetual  winter.  We 


16  THE   PITH    OF   ASTRONOMY 

are  roofed  over  by  the  air  that  treas- 
ures the  heat,  and  floored  beneath  by  a 
stratum  both  absorptive  and  retentive 
of  heat — so  that  between  the  earth  and 
air  our  vegetation  and  crops  grow  and 
ripen. 

We  owe  these  obligations  and  many 
more  to  the  sun ;  it  is  little  wonder, 
then,  that  men  have  bowed  down  and 
worshipped  it  in  all  ages. 


MERCURY 

THE  planet  Mercury  is  36,000,000 
miles  from  the  sun. 

Its  diameter  is  3000  miles. 

Its  year  is  88  days. 

It  moves  in  its  orbit  at  a  speed  of  29 
miles  per  second. 

Its  day  is  supposed  to  be  2±  hours 
and  5  minutes. 

Mercury  is  the  nearest  planet  to  the 
sun.  It  can  never  be  seen  by  the  naked 
eye  except  in  the  west  a  short  time 
after  sunset,  and  in  the  east  a  little  be- 
fore sunrise.  To  see  it,  all  the  con- 
ditions must  be  favorable;  it  is  said 
that  the  celebrated  astronomer  Coperni- 
cus never  had  the  good  fortune  to  see  it. 


18  THE   PITH    OF   ASTRONOMY 

It  is  usually  lost  in  the  glare  of  the 
sun,  owing  to  its  close  proximity,  and 
consequently  the  difficulty  of  observ- 
ing it  is  great.  Astronomers  have  not 
agreed  on  the  length  of  its  days  or  the 
density  of  its  atmosphere. 

Mercury  is  the  densest  member  of 
the  solar  system. 

Mercury  has  no  moon. 

"When  Mercury  comes  between  the 
earth  and  sun,  near  the  line  where  the 
plane  of  their  orbits  cut  each  other  by 
reason  of  their  inclination,  the  dark 
body  of  Mercury  is  seen  on  the  bright 
surface  of  the  sun.  This  is  called  a 
transit,  and  it  occupies  several  hours  in 
its  completion,  depending  on  the  cir- 
cumstances of  the  transit. 

The  next  transit  seen  in  this  country 
will  occur  November  4,  1901. 


VENUS 

VENUS  is  67,000,000  miles  from  the 
sun,  and  is  the  second  planet  from  it. 

Its  diameter  is  7700  miles. 

Its  year  is  225  days. 

Its  orbital  speed  is  22  miles  per  sec- 
ond. 

Its  day  is  supposed  to  be  a  little  over 
23  hours. 

It  is  sometimes  called  the  evening 
star,  and,  as  we  see  it,  is  the  most  mag- 
nificent planet  in  the  solar  system,  ex- 
ceeding in  light  and  beauty  the  bright- 
est stars ;  its  light  is  so  vivid  that  it 
casts  a  perceptible  shadow,  and  we  some- 
times see  it  in  full  daylight. 


20  THE  PITH    OF    ASTRONOMY 

The  orbit  of  Yenus  is  almost  a  per- 
fect circle;  the  paths  of  all  the  other 
planets  are  more  elliptical. 

Venus  has  an  atmosphere.  It  has  no 
moon.  Authorities  do  not  agree  on  the 
length  of  the  day  on  Yenus,  owing  to 
the  difficulty  of  observing  the  surface 
of  the  planet  through  its  thick  atmos- 
phere. 

An  astronomical  observation  was 
made  of  Yenus  in  Babylon  in  685  B.C. 
It  is  written  on  a  brick,  which  is  now  in 
the  British  Museum. 

The  heat  on  Yenus  is  much  greater 
than  on  our  earth.  Its  water  is  sup- 
posed to  be  in  the  form  of  dry  steam, 
the  dense  atmosphere  causing  the  re- 
tention of  its  heat. 

The  dimensions  of  Yenus  make  it  a 
veritable  twin  of  our  earth,  and  in  many 
other  respects  they  resemble  each  other. 


VENUS  21 

Land  and  water  are  believed  to  exist, 
and  some  of  the  appearances  suggest 
the  existence  of  mountains   27  miles 
high. 
Yenus  is  the  ideal  vision  of  the  skies. 


THE   EARTH 

"  The  globe  terrestrial,  with  its  slanting  poles, 
And  all  its  pond'rous  load,  unwearied  rolls." 

THE  earth  is  93,000,000  miles  from 
the  sun,  and  is  the  third  planet  from  it. 

The  diameter  of  the  earth  is  8000 
miles.  (To  be  exact,  7926  miles  through 
the  equator.) 

It  revolves  round  the  sun  in  365  days, 
6  hours,  9  minutes,  and  9  seconds. 

Its  circumference  is  a  little  less  than 
25,000  miles. 

It  turns  on  its  axis  in  23  hours,  56 
minutes,  and  4  seconds. 

The  earth  is  some  3,000,000  miles 
nearer  the  sun  in  winter  than  it  is  in 


THE    EARTH  23 

summer;  consequently,  the  sun  looks 
larger  to  our  eyes  at  that  time,  but  the 
solar  rays  strike  the  earth  in  our  hemi- 
sphere more  obliquely  in  winter  and  do 
not  produce  so  much  heat. 

The  earth  is  as  dense  or  heavy  as  it 
would  be  if  composed  entirely  of  metal- 
lic iron  ore,  which  is  five  times  heavier 
than  water. 

Geologists  tell  us  that  it  is  hundreds 
of  millions  of  years  since  the  earth  was 
in  the  condition  of  a  molten  mass  of 
matter,  with  its  crust  just  commencing 
to  form  as  it  slowly  cooled. 

The  earth  is  more  rigid  than  glass, 
therefore  probably  no  large  proportion 
of  its  interior  can  be  liquid,  as  many 
have  supposed  it  to  be.  Its  interior 
must  be  largely  metallic. 

It  is  estimated  that  the  earth  is  in- 
habited by  fifteen  hundred  millions  of 


24  THE   PITH    OF   ASTRONOMY 

people.  Its  surface  contains  187^00,000 
square  miles,  three-quarters  of  which 
are  water. 

It  may  be  estimated  that  something 
like  four  hundred  thousand  millions  of 
men  and  women  have  lived  since  the 
advent  of  mankind. 

This  globe  has  eleven  known  mo- 
tions. Among  the  most  easily  under- 
stood is  its  daily  rotation  on  its  axis, 
the  passage  over  its  orbit  round  the 
sun,  and  the  motion  towards  the  bright 
star  Vega,  towards  which  the  entire 
solar  system  is  flying. 

Viewed  from  Venus  and  Mercury, 
the  earth  is  the  'brightest  star  of  the 
firmament,  lit  up  by  reflection  from  the 
sun. 

The  earth  is  flattened  at  the  poles  27 
miles,  and  this  leads  to  the  truthful  but 
paradoxical  statement  that  the  Missis- 


THE    EAKTH  25 

sippi  Eiver  runs  up  hill,  as  its  mouth  is 
three  miles  farther  from  the  centre  of 
the  earth  than  its  source. 

We  fly  through  space  at  the  rate  of 
more  than  18  miles  a  second,  seventy- 
five  times  faster  than  a  cannon-ball, 
and  pass  over  our  orbit  round  the  sun 
in  a  year,  the  orbit  containing  585,- 
000,000  miles.  We  thus  travel  1,500,- 
000  miles  daily  through  the  skies,  but 
never  over  the  same  path,  as  we  are 
chained  to  the  sun  and  follow  its  or- 
bit. 

We  would  be  blown  from  the  earth 
like  dust  did  we  not  share  its  momen- 
tum, or  if  the  envelope  of  air  did  not 
proceed  with  us. 

Were  the  earth  suddenly  arrested  in 
its  flight,  or  if  it  came  into  collision 
with  another  large  body,  the  heat  pro- 
duced would  be  so  tremendous  that 


26  THE    PITH    OF   ASTRONOMY 

the  entire  globe  would  be  instantly 
turned  into  gas  and  form  a  floating 
nebula. 

A  soap-bubble  in  the  wind  could 
hardly  be  more  flexible  and  sensitive 
to  influence  than  the  earth.  If  the 
water  became  more  dense,  or  if  the 
globe  were  to  revolve  faster,  the  oceans 
would  rush  to  the  equator,  burying  the 
tallest  mountains  and  leaving  the  polar 
regions  bare.  If  the  water  should  be- 
come lighter,  or  the  earth  rotate  more 
slowly,  the  poles  would  be  submerged 
and  the  bottom  of  the  equatorial  oceans 
become  an  arid  waste.  Ko  balance 
turning  to  the  1000th  of  a  grain  is 
more  delicate  than  the  poise  of  forces 
on  this  globe.  Laplace  has  given 
us  indisputable  proof  that  the  period 
of  the  earth's  axial  rotation  has  not 
changed  the  100th  part  of  a  second 


THE    EARTH  27 

of  time  in  2000  years.  Man  cannot 
make  a  clock  that  will  tell  the  hours  for 
a  single  day  with  the  exactness  that 
this  vast  globe  has  done  for  all  recorded 
time. 

Sunrise  greets  a  new  1000  miles  at 
every  hour;  the  glories  of  the  sunset 
follow  over  an  equal  space  some  12,000 
miles  behind.  While  the  east  and  west 
are  gorgeous  with  sunrise  and  sunset, 
the  north  and  south  are  often  more  re- 
markable still  with  their  aurora  bore- 
alis  and  Magellanic  clouds. 

We  in  this  latitude  know  but  little 
of  the  glorious  "Northern  dawn."  It 
prevails  near  the  arctic  circle,  and 
there  takes  many  forms  —  cloud-like, 
arched,  straight.  It  streams  like  ban- 
ners, Avaves  like  curtains  in  the  wind ; 
it  is  inconstant,  and  is  either  the  cause 
or  result  of  electric  currents  -,  it  is  often 


28  THE  PITH  or  ASTRONOMY 

far  above  our  atmosphere,  sometimes  as 
high  as  GOO  miles. 

The  realm  of  this  royal  splendor  is 
yet  an  unconquered  world,  waiting  fox 
its  Alexander. 


THE  MOON 

"As  when  the  Moon,  refulgent  lamp  of  night, 
O'er  heaven's  clear  azure  spreads  her  sacred 

light, 

Around  her  throne  the  vivid  planets  roll, 
And  stars  unnumbered  gild  the  glowing  pole." 

THE  moon  revolves  round  the  earth 
at  a  mean  distance  of  nearly  239,000 
miles. 

Its  diameter  is  2160  miles. 

The  volume  or  bulk  of  the  earth  is 
almost  fifty  times  greater  than  that  of 
the  moon,  and  it  would  take  60,000,000 
of  moons  to  equal  the  sun. 

The  surface  of  the  moon  contains 
about  the  same  number  of  square  miles 


30  THE   PITH    OF    ASTRONOMY 

that  are  found  in  North  and  South 
America. 

It  completes  its  revolution  round  the 
earth  in  27  days,  7  hours,  43  minutes, 
and  11  seconds,  which  is  its  sidere- 
al month ;  the  ordinary  month,  from 
new  moon  to  new  moon  again,  is  29 
days,  12  hours,  44  minutes,  and  2  sec- 
onds. 

It  revolves  on  its  axis  exactly  in  a 
sidereal  month,  and  therefore  always 
presents  almost  the  same  face  to  the 
earth;  thus  we  never  have  seen  the 
far  side  of  the  moon,  nor  will  we  ever 
see  it.  This  circumstance  causes  the 
moon  to  have  the  longest  day  (caused 
by  the  sun's  light)  of  any  known  celes- 
tial body— there  are  but  twelve  of  them 
in  our  year. 

The  moon  travels  round  the  earth  in 
its  orbit  at  a  speed  of  37  miles  a  minute, 


THE   MOON  31 

and  its  orbit  contains  about  1,500,000 
miles. 

The  moon  varies  in  size  to  the  eye,  as 
the  distance  from  us  varies  to  the  ex- 
tent of  25,000  miles  in  the  course  of  a 
month. 

When  the  moon  is  between  us  and 
the  sun  that  side  which  faces  us  is  not 
lit  up  by  reflected  light,  and  we  do  not 
see  it ;  when  it  forms  a  right  angle 
with  the  sun  we  see  half  of  its  face,  and 
when  we  are  between  it  and  the  sun 
we  see  it  as  the  full  moon. 

A  man  weighing  155  pounds  here 
would  weigh  but  26  pounds  on  the 
moon,  and  could,  consequently,  jump  in- 
credible distances. 

The  dimensions  of  the  moon  as  com- 
pared with  those  of  the  earth  are  far 
greater  than  those  of  any  other  satel- 
lite in  proportion  to  its  primary. 


32  THE    PITH    OF   ASTRONOMY 

The  moon's  day  (caused  by  the  sun's 
light)  is  almost  thirty  times  as  long  as 
ours,  and  consists  of  fifteen  days  of  day- 
light and  fifteen  days  of  darkness. 

As  it  has  no  atmosphere  to  protect 
it  from  the  sun's  rays  its  heat  in  day- 
light is  intense — strong  enough  to  boil 
water — while  at  night  the  cold  is  fright- 
ful, being  several  hundred  degrees  be- 
low zero.  Lord  Kosse  estimates  the 
difference  between  day  and  night  to  be 
500  degrees. 

The  moon  is  a  dead  cinder ;  if  it  ever 
had  air  and  water,  which  it  probably 
had,  they  are  now  absorbed  in  the 
porous  lava  that  covers  its  surface. 

In  consequence  of  the  small  gravity 
at  the  moon,  the  absence  of  the  expan- 
sive power  of  ice  and  the  levelling  influ- 
ence of  rains,  precipices  stand,  moun- 
tains shoot  up  like  needles,  and  cavities 


THE   MOON 


three  miles  deep  remain  unfilled  ;  these 
conditions  give  the  moon  grand  and 
savage  scenery,  such  as  cannot  be  found 
on  the  earth.  It  has  twenty-eight  moun- 
tains higher  than  Mount  Blanc  ;  ten  of 
these  are  over  18,000  feet  high,  the 
two  highest,  Mounts  Leibnitz  and  Dor- 
fel,  being  almost  25,000  feet  each. 

These  mountains  have  been  measured 
with  greater  accuracy  than  any  of  our 
own,  and  in  a  general  way  the  maps 
made  of  the  moon  are  more  reliable 
than  those  made  of  the  earth.  The  ex- 
tinct volcanic  craters  on  the  moon  are 
enormous.  The  crater  of  Clavius  has  a 
diameter  of  130  miles.  By  the  aid  of 
powerful  telescopes  33,000  craters  have 
been  counted  on  the  side  of  the  moon 
which  we  see. 

We  are  indebted  to  the  moon  for 
many  things ;  but  the  greatest  of  these 


34  THE   PITH    OF   ASTRONOMY 

is  that  it  is  principally  owing  to  its 
attraction  that  we  have  the  purifying 
motion  of  the  seas  known  as  tides. 
Without  these  daily  currents  the  oceans 
would  become  stagnant  and  unhealthy 
to  such  an  extent  that  we  could  not 
live  on  their  shores. 


MARS 

TILE  planet  Mars  is  141,000,000  miles 
from  the  sun. 

Its  diameter  is  4200  miles. 

Its  years  contains  687  days. 

Its  mean  distance  from  the  earth  is 
48,000,000  miles. 

The  day  on  Mars  is  half  an  hour 
longer  than  ours,  or  about  24  hours  and 
37  minutes. 

It  has  two  moons. 

It  moves  at  the  rate  of  15  miles  a 
second. 

Mars  is  the  fourth  planet  from  the 
sun,  and  is  called  the  red  planet,  from 
its  well-known  color. 


36  THE   PITH    OF   ASTKONOMY 

The  combination  of  its  motion  with 
ours  causes  it  to  pass  behind  us,  or  op- 
posite to  the  sun,  once  in  two  years. 
For  two  months  at  this  period  it  is  best 
seen,  and  appears  as  a  red  lamp  in  the 
sky ;  at  other  times  it  looks  small  and 
unimportant. 

Its  density  and  size  are  less  tbaii  ours  ; 
a  man  weighing  200  pounds  here  would 
weigh  but  75  pounds  on  Mars. 

The  orbit  of  this  planet  is  decided- 
ly elliptical;  it  is  26,000,000  miles 
nearer  the  sun  at  the  nearest  part  of 
its  orbit  than  it  is  at  the  farthest,  con- 
sequently the  variation  in  heat  from 
this  cause  alone  is  considerable. 

In  many  ways  Mars  resembles  our 
earth  :  it  has  atmosphere,  seasons,  land, 
water,  storms,  clouds,  and  mountains ; 
it  also  snows  and  rains  on  Mars,  as  it 
does  with  us.  Snow  and  ice  cover 


sKUVATIOXS    OF    MAKS    SHOWING    ITS    CHANGf 


MAKS  37 

both  its  poles,  and  produce  great  white 
patches  at  those  points,  which  are  clear- 
ly seen  through  a  large  telescope ;  such 
an  instrument  also  shows  the  markings 
on  the  land  known  as  the  canals.  Fairly 
accurate  maps  have  been  made  of  Mars, 
showing  its  natural  divisions  of  land 
and  water  to  be  about  equal. 

It  has  been  suggested  that  the  vege- 
tation on  Mars,  for  the  most  part  at 
least,  is  yellow  or  orange,  instead  of 
green,  as  with  us,  thus  giving  the  planet 
its  color. 

It  is  but  3TOO  miles  from  the  surface 
of  Mars  to  its  nearest  moon,  and  that 
satellite  revolves  round  it  in  seven 
hours  and  a  half,  showing  all  the 
phases  of  our  moon  in  a  night ;  to  an 
inhabitant  of  Mars  it  has  the  appear- 
ance of  an  enormous  shooting  -  star 
slowly  moving  through  the  sky,  and 


204808 


38  THE   PITH    OF   ASTRONOMY 

would  take  our  breath  away  if  we  saw 
anything  like  it  from  our  earth. 

Percival  Lowell,  of  Boston,  has  late- 
ly devoted  his  life  and  fortune  to  the 
observation  of  Mars.  He  has  erected 
an  extensive  observatory  at  Flagstaff, 
Arizona,  and  has  been  using  it  for  this 
purpose  for  two  or  three  years.  He  is 
now  providing  a  special  telescope  with 
a  magnifying  power  of  2400  diame- 
ters, for  the  purpose  of  examining  this 
planet. 

Mr.  Lowell's  extended  observations 
lead  him  to  believe  that  Mars  is  in- 
habited by  a  highly  civilized  race  of 
beings,  who  are  now  carrying  on  great 
engineering  works,  including  the  famous 
canals,  which  have  been  the  subject  of 
so  much  speculation. 


JUPITER 

"More    yet    remote    from   day's    all -cheering 

source, 

Vast  Jupiter  performs  his  constant  course ; 
Five   friendly   moons,  with  borrowed  lustre, 

rise, 
Bestow    their   beams    benign,    and   light    his 

skies." 

JUPITER  is  the  fifth  planet  from  the 
sun,  and  revolves  round  it  at  a  mean 
distance  of  483,000,000  miles. 

Its  year  is  almost  twelve  of  ours — or 
exactly  11  years,  10  months,  and  17 
days. 

Its  diameter  is  88,000  miles. 

Its  volume  is  about  1300  times  that 
of  the  earth. 


40  THE   PITH    OF  ASTRONOMY 

It  is  390,000,000  miles  from  us  when 
both  Jupiter  and  the  earth  are  on  the 
same  side  of  the  sun. 

The  day  on  Jupiter  is  less  than  ten 
hours. 

It  moves  over  its  orbit  at  the  rate  of 
eight  miles  a  second. 

Its  light  is  so  brilliant  that  it  casts  a 
shadow. 

A  man  weighing  200  pounds  here 
would,  if  carried  to  Jupiter,  turn  the 
scales  at  500  pounds. 

A  web  of  cloth  as  long  as  from  the 
earth  to  our  moon  would  fall  short  of 
encircling  this  great  planet.  Jupiter 
is  flattened  at  the  poles  and  bulges  at 
the  equator,  owing  to  the  speed  of  its 
rotary  motion,  and  if  it  rotated  a  little 
faster  it  could  not  keep  itself  together, 
but  would  burst,  and  be  spread  on  the 
skies  like  a  coat  of  paint. 


THE   PLANET    JUPITER    AND    ITS    BELTS 


JUPITER  41 

Its  days  are  so  short,  in  consequence 
of  the  rapidity  of  its  rotation,  that  its 
year  contains  10,455  of  them. 

As  its  axis  is  vertical,  there  are  no 
seasons  such  as  we  have,  the  most  of  its 
surface  remaining  in  eternal  spring. 

The  clouds  in  the  thick  atmosphere 
take  the  form  of  immense  belts,  on 
which  spots  appear,  both  of  which  can 
be  plainly  seen  through  a  telescope; 
the  atmosphere  over  the  equator  moves 
faster  than  the  air  north  or  south  of  it, 
producing  the  effect  of  a  violent  wind 
constantly  blowing  over  its  equatorial 
zone  at  a  velocity  of  250  miles  an  hour. 

Jupiter  has  five  moons;  three  of 
them  are  much  larger  than  our  moon, 
and  one  is  larger  than  Mercury,  having 
a  diameter  of  3600  miles.  The  near- 
est is  112,000  miles  from  the  planet, 
and  the  most  distant  is  1,189,000  miles 


43  THE   PITH    OF   ASTRONOMY 

away;  they  travel  over  their  orbits 
with  varying  speed,  and,  with  their 
primary,  are  known  as  the  Jovian  sys- 
tem. It  is  very  probable  that  these 
worlds  are  inhabited  —  more  probable 
than  that  Jupiter  has  now  any  inhabi- 
tants— as  they  have  atmospheres  and 
some  of  the  requirements  for  sustaining 
life.  Jupiter  seems  to  be  a  world  in 
process  of  formation,  cooling  in  prepa- 
ration for  the  race  that  may  at  some 
future  time  occupy  it.  It  has  been  said 
that  this  planet  represents  to-morrow, 
the  earth  to-day,  and  our  moon  yester- 
day. 

The  magnificence  of  the  celestial 
spectacle  presented  by  the  Jovian  sys- 
tem is  beyond  description,  as  seen  by 
one  standing  on  the  nearest  moon. 
Jupiter  presents  an  immense  luminous 
disk,  more  than  3000  times  the  size  of 


JUPITER  43 

our  moon,  while  the  sight  is  diversified 
by  the  other  four  worlds  flying  round 
in  their  orbits,  and  all  comparatively 
close  to  the  observer.  These  moons  have 
a  variety  of  color ;  two  are  blue,  one  is 
yellow,  and  one  red.  Jupiter  spins  like 
a  top  in  the  centre,  the  moons  rush 
round  it,  and  the  whole  procession 
sweeps  through  the  skies  at  the  rate  of 
500  miles  a  minute.  Yet  the  disclosure 
of  all  this  power,  skill,  and  stability  is 
but  entering  the  vestibule  of  astronomy. 


SATURN 

"  One  moon  to  us  reflects  its  cheerful  light, 
There,  eight  attendants  brighten  up  the  night; 
Here,  the  blue  firmament  bedecked  with  stars, 
There,  overhead,  a  lucid  arch  appears." 

SATURN'S  mean  distance  from  the  sun 
is  883,000,000  miles. 

It  is  the  sixth  planet  from  the  sun. 

Its  diameter  is  75,000  miles,  and  it  is 
the  largest  planet  excepting  Jupiter. 

It  is  790,000,000  miles  from  the 
earth. 

It  revolves  round  the  sun  in  29  years 
and  5  months. 

Its  volume  is  697  times  that  of  the 
earth. 


SATURN  45 

Its  day  is  10  hours,  14  minutes,  and 
24  seconds. 

It  has  25,000  days  in  its  year. 

Its  orbital  speed  is  6  miles  a  second. 

Eight  moons  revolve  round  it ;  no 
other  solar  planet  has  so  many.  In 
composition  it  is  lighter  than  water, 
and  it  has  a  dense  atmosphere. 

The  poles  are  flattened  one-tenth  of 
its  diameter,  which  is  a  larger  propor- 
tion than  on  any  of  the  other  planets. 

On  account  of  the  velocity  of  its  ro- 
tary motion,  gravity  varies  greatly  on 
the  surface;  the  centrifugal  force  at 
the  equator  antagonizes  gravitation  to 
such  an  extent  that  while  a  man  would 
weigh  less  there  than  he  does  here,  at 
Saturn's  pole  he  would  weigh  more 
than  on  the  earth. 

Our  opportunities  for  seeing  Saturn 
vary  greatly.  As  the  earth  at  one  part 


4S  THE   PITH    OF   ASTRONOMY 

of  its  orbit  presents  its  south  pole  to 
the  sun,  then  its  equator,  then  the  north 
pole,  so  does  Saturn ;  and  we,  in  the  di- 
rection of  the  sun,  see  the  south  side  of 
the  rings  inclined  at  an  angle;  next, 
the  edge  of  the  rings  appears  like  a  fine 
thread  of  light,  and  then  the  north  side 
at  a  similar  inclination.  It  occupies  fif- 
teen years  in  making  all  these  changes. 

Galileo,  with  the  first  telescope,  dis- 
covered Saturn's  ring  in  1610.  In  1612 
the  thin  edge  was  turned  towards  the 
earth,  and  with  his  imperfect  glass  he 
could  not  see  it ;  greatly  discouraged, 
and  believing  he  had  been  deceived,  he 
exclaimed,  "  Is  it  possible  some  demon 
has  mocked  me?"  He  would  never 
look  at  the  planet  again,  and  died  with- 
out knowing  that  he  had  discovered  the 
ring. 

Saturn  is  surrounded  by  an  enormous 


SATUEN  47 

fiat,  luminous  ring,  which  is  one  of  the 
greatest  wonders  of  the  heavens,  and 
when  seen  through  a  telescope  it  com- 
pares favorably  with  any  celestial  sight. 

This  ring  is  about  175,000  miles  in 
diameter,  and  the  average  estimate  of 
its  thickness  is  75  miles. 

The  composition  of  the  ring  has  caused 
much  speculation.  Laplace  demonstrat- 
ed that  it  cannot  be  solid  and  survive 
an  hour ;  Peirce  showed  it  could  not 
be  fluid  and  continue;  other  authori- 
ties proved  the  impossibility  of  its  be- 
ing composed  of  gas ;  and  finally  Max- 
well showed  it  must  be  composed  of 
clouds  of  satellites,  some  of  them  prob- 
ably not  larger  than  an  orange,  but  all  of 
them  too  small  to  be  seen  individually, 
and  too  near  together  for  the  spaces  to 
be  discerned.  This  theory  is  now  ac- 
cepted as  correct. 


48  THE   PITH    OF   ASTRONOMY 

The  ring  has  three  divisions ;  the  in- 
nermost ring  is  dusky  and  transparent ; 
in  contact  with  it  is  the  brightest  ring, 
called  ring  B;  then  comes  a  gap,  and 
then  the  outer  ring,  known  as  ring  A. 
There  are  other  divisions,  but  they  are 
not  permanent. 

If  the  scenery  of  Jupiter  is  magnifi- 
cent, that  of  Saturn  is  unique.  Here 
we  have  a  universe,  a  colossal  system,  a 
wreath  of  vast  proportions  turned  to 
silver  by  the  reflection  from  the  sun, 
and  eight  moons  revolving  outside  its 
limits — travelling  like  pearls  strung  on 
a  silver  thread.  No  one  has  ever  seen 
Saturn  come  into  the  field  of  a  large 
telescope  for  the  first  time  without  sa- 
luting the  spectacle  with  exclamations 
of  surprise  and  delight.  Saturn  is  the 
wonder  of  the  solar  system. 


URANUS 

UKANUS  is  the  seventh  planet  from 
the  sun,  and  comes  fourth  in  the  or- 
der of  size.  Its  mean  distance  from 
the  sun  is  seventeen  hundred  and  sev- 
enty -  eight  millions  of  miles,  and 
from  the  earth  it  is  sixteen  hundred 
and  eighty -five  millions  of  miles  dis- 
tant. 

Owing  to  its  great  distance,  astrono- 
mers have  not  been  able  to  determine 
the  length  of  its  day,  but  it  has  been 
estimated  at  11  hours. 

Its  diameter  is  31,000  miles. 

It  takes  84  years  to  make  its  revolu- 
tion round  the  sun. 


60  THE   PITH   OF   ASTRONOMY 

Its  volume  is  G9  times  that  of  the 
earth. 

It  has  an  atmosphere. 

It  speeds  over  its  orbit  at  the  rate  of 
4  miles  a  second. 

There  is  a  great  surprise  in  store  for 
the  observers  of  this  planet.  It  has 
four  moons,  and  they  revolve  round  it 
from  east  to  west,  differing  in  this  re- 
spect from  the  other  planets,  whose 
satellites  revolve  from  west  to  east, 
and  in  about  the  plane  of  their  equa- 
tors, while  the  followers  of  Uranus  re- 
volve in  a  plane  nearly  perpendicular 
to  that  in  which  the  planet  moves — i.  e., 
this  system  rolls  like  a  carriage-wheel, 
while  all  the  others  spin  like  roulette- 
wheels,  the  motion  of  the  former  being 
backward. 

Uranus  may  be  seen  by  the  naked 
eye,  under  favorable  circumstances,  as 


UKANUS  51 

a  sea-green  star  of  about  the  sixth 
magnitude.  Up  to  the  time  when  large 
telescopes  were  first  used  Uranus  was 
mistaken  for  a  fixed  star  by  those  who 
observed  it. 

On  the  night  of  March  13,  1781,  Sir 
William  Herschel  saw  through  his  glass 
that  it  had  a  disk  and  moved  slowly 
through  the  heavens;  this  celebrated 
discovery  deposed  Saturn  as  the  fron- 
tier planet,  a  position  it  had  held  from 
the  beginning.  As  we  will  see  in  the 
succeeding  chapter,  this  led  to  another 
discovery,  and  Uranus  had,  in  turn,  to 
give  way  to  Neptune  as  the  sentinel  of 
the  solar  system. 

Herschel  called  his  discovery  Georgi- 
um  Sidus,  in  honor  of  his  king  and  pa- 
tron ;  the  people  called  it  Herschel,  but 
astronomers  finally  decided  on  its  pres- 
ent classical  name  as  the  proper  one. 


NEPTUNE 

"Who  there  inhabit  must  have  other  powers, 
Juices,  and  veins,  and  sense,  and  life  than  ours  ; 
One  moment's  cold  like  theirs  would  pierce  the 

bone, 
Freeze  the  heart's-blood,  and  turn  us  all  to 

stone." 

THIS  planet  is  the  eighth  from  the 
sun,  and  is  third  in  mass  and  volume. 

Its  mean  distance  from  the  sun  is 
two  thousand  eight  hundred  millions  of 
miles,  and  from  the  earth  two  thou- 
sand seven  hundred  and  seven  millions. 

Its  diameter  is  37,000  miles. 

It  revolves  round  the  sun  in  164  of 
our  years. 


NEPTUNE  53 

It  has  an  atmosphere. 

Neptune  is  attended  by  one  moon, 
which  moves  round  it  in  about  six 
days,  at  a  distance  of  260,000  miles ;  and 
it  is  remarkable  that  its  motion  is  ret- 
rograde. 

The  telescopes  at  present  in  use  do 
not  show  Neptune  to  us  clearly  enough 
to  determine  its  diurnal  motion,  so  the 
length  of  its  day  is  unknown. 

It  has  the  longest  orbit  and  the  slow- 
est motion  of  any  planet,  and  although 
it  travels  over  its  annual  path  of  sev- 
enteen thousand  millions  of  miles  at 
the  rate  of  200  miles  a  minute,  it  may 
still  be  called  the  tortoise  of  the  skies. 

Since  its  discovery  it  has  not  as  yet 
completed  a  third  of  its  first  rotation 
round  the  sun,  and  as  it  will  not  finish  its 
initial  trip  till  the  year  2010,  no  one  at 
present  alive  will  live  to  see  that  event. 


54  THE   PITH   OF   ASTKONOMY 

Neptune  is  invisible  to  the  naked 
eye;  when  seen  through  a  telescope 
the  light  we  see  has  travelled  from  the 
sun  to  it  and  returned  to  us  by  reflec- 
tion, a  double  trip  of  five  thousand  five 
hundred  and  seven  millions  of  miles,  in 
something  over  eight  hours.  It  would 
take  an  express  train  over  10,000  years 
to  accomplish  this  task. 

There  is  no  object-lesson  in  the  won- 
ders of  light  that  we  can  grasp  so  easily 
as  this ;  it  is  the  longest  return  of  light 
that  the  heavens  afford  us. 

Neptune  is  our  frontier  planet,  and  was 
discovered  simultaneously  by  Adams, 
of  England,  and  Leverrier,  of  France, 
in  the  autumn  of  1846.  Both  believed 
it  to  exist  from  observing  that  its 
neighbor,  Uranus,  was  retarded  in  its 
orbit  by  the  attraction  of  some  great 
unseen  world.  Both  of  these  men  gave 


NEPTUNE  55 

their  calculations  to  astronomers  pos- 
sessing large  telescopes,  directing  them 
where  to  look  for  the  great  unknown — • 
and  both  were  successful. 

This,  the  last  great  discovery  in  as- 
tronomy, was  sensational  in  every  way, 
and  is  a  standing  monument  to  the 
highest  reasoning  powers  of  the  hu- 
man mind.  Had  it  been  discovered 
by  a  mere  survey  of  the  heavens,  one 
of  man's  greatest  achievements  would 
never  have  seen  the  light  of  day. 


COMETS 

THE  word  comet  is  derived  from  the 
Latin  word  coma,  meaning  hair.  Com- 
ets are  celestial  bodies  which  move 
round  the  sun  in  greatly  elongated  or- 
bits, usually  elliptical  or  parabolic. 

A  comet  usually  consists  of  a  brill- 
iant point  surrounded  by  nebulous  light, 
which  extends  backward  in  the  form  of 
a  tail  or  train.  The  nucleus  or  head 
has  an  undetermined  amount  of  solid- 
ity, but  stars  may  be  clearly  seen 
through  all  comets. 

Of  the  physical  condition  of  comets 
little  is  at  present  known.  Professor 
Young,  of  Princeton,  states  that  a  comet 


THK  COMET  OF  1881,  AS  SEKN  THKOrOH  PROFESS 
DRAPER'S  TELESCOPE,  JUNE  27 


COMETS  57 

is  nothing  but  a  "  sand-bank";  that  is,  it 
is  a  swarm  of  solid  particles  of  unknown 
size  and  widely  separate,  say  pinheads 
several  hundred  feet  apart,  each  particle 
carrying  with  it  an  envelope  of  gas, 
largely  hydrocarbon,  in  which  gas-light 
is  produced,  either  by  electrical  dis- 
charges between  the  particles  or  by 
some  other  light,  the  evolving  action 
due  to  the  sun's  influence.  This  hypoth- 
esis derives  its  chief  plausibility  from 
the  modern  discovery  of  the  close  rela- 
tionship between  meteors  and  comets. 

He  also  states  that  comets  may  hurt 
us  in  two  ways,  either  by  actually  strik- 
ing the  earth  or  by  falling  into  the  sun, 
and  thus  producing  such  an  increase  of 
solar  heat  as  to  burn  us  up. 

In  regard  to  the  possibility  of  a  colli- 
sion with  a  comet,  Professor  Pickering, 
of  Harvard,  says  that  it  must  be  admitted 


58  THE   PITH    OF   ASTRONOMY 

that  such  an  event  is  possible;  if  the 
earth  lasts  long  enough  such  a  thing  is 
practically  sure  to  happen,  for  there  are 
several  comets'  orbits  which  pass  nearer 
to  the  earth's  orbit  than  the  semidiam- 
eter  of  the  comet's  head,  and  at  some 
time  the  earth  and  comet  will  certainly 
come  together.  Such  encounters  will, 
however,  be  rare.  If  we  accept  the  esti- 
mate of  Babinet,  they  will  occur  once 
in  15,000,000  years,  in  the  long  run. 

It  is  impossible  to  estimate,  for  want 
of  sure  knowledge  of  the  state  of  aggre- 
gation of  the  matter  composing  a  comet, 
when  such  a  conflict  will  take  place. 
If  we  accept  the  modern  theory,  and  if 
this  theory  be  true,  everything  depends 
on  the  size  of  the  separate  solid  parti- 
cles which  form  the  main  part  of  the 
comet's  mass.  If  they  weigh  tons,  the 
bombardment  would  be  very  serious, 


COMETS  59 

but  if,  as  seems  more  likely,  the  parti- 
cles are  smaller  than  pinheads,  the  re- 
sult would  be  simply  a  grand  meteoric 
shower. 

Comets  may  be  classed  under  two 
heads:  those  that  return  in  their  pe- 
riod— i.  e.,  in  a  stated  number  of  years 
(the  orbit  of  this  variety  is  always  in 
the  form  of  an  ellipse) — and  those  that 
travel  in  a  parabola  whose  direction 
will  cause  them  to  run  out  into  space 
and  never  return  to  the  sun.  These 
are  named,  respectively,  periodic  and 
parabolic  comets. 

Comets  are  further  divided  into  those 
whose  orbits  lie  within  the  solar  system, 
and  consequently  have  a  short  period, 
returning  within  a  few  years,  and  those 
whose  path  and  direction  carry  them 
far  beyond  our  system,  returning  after 
the  lapse  of  centuries. 


60  THE    PITH    OF   ASTRONOMY 

They  are  still  further  divided  into 
those  that  can  be  seen  by  the  naked 
eye  and  those  that  can  only  be  seen  by 
the  aid  of  a  telescope;  the  latter  are 
known  as  telescopic  comets,  and  the 
majority  belong  to  this  class. 

It  is  estimated  that  20,000  comets 
have  passed  within  sight  of  the  earth 
since  the  birth  of  Christ ;  of  these  800 
have  been  observed,  but  it  is  reasonable 
to  suppose  that  there  are  thousands  of 
millions  of  them  moving  in  all  direc- 
tions in  infinite  space. 

All  comets  that  visit  the  solar  sys- 
tem and  turn  on  the  sun  are  raised  to 
incandescence  from  its  heat  when  ap- 
proaching and  passing  it ;  it  therefore 
naturally  follows  that  they  become 
more  brilliant  when  in  its  vicinity. 

The  comets  of  1680  and  1843  were 
perhaps  the  most  sensational  that  have 


COMETS  61 

ever  been  seen  by  men ;  they  were  nearly 
alike  in  splendor  and  dimensions.  The 
latter,  flying  at  the  inconceivable  speed 
of  340  miles  a  second,  turned  round  the 
sun  from  half-past  nine  till  half -past 
eleven  on  the  morning  of  February  27, 
1843.  This  is  the  greatest  velocity  that 
has  been  definitely  measured  by  astron- 
omers ;  turning  the  celestial  stake-post 
gave  them  the  desired  opportunity.  Its 
tail  was  straight,  and  measured  198,000,- 
000  miles,  and  it  is  one  of  the  won- 
ders of  this  observation  that  the  tail 
was  always  opposite  to  the  sun,  and 
seemed  not  to  be  broken  off  or  scat- 
tered on  the  skies  when  making  such 
an  abrupt  turn  in  two  hours.  Astron- 
omers have  calculated  that  it  will  re- 
turn to  us  in  the  year  2219 ;  we  may 
promise  for  our  descendants  that  it  will 
have  a  memorable  reception. 


62  THE   PITH   OF   ASTRONOMY 

The  comet  of  Donati,  in  1858,  was 
the  most  beautiful  that  has  been  ob- 
served ;  it  had  a  brilliant  head,  and  car- 
ried with  it  a  curved  tail  measuring 
65,000,000  miles.  Its  period  is  about 
2000  years. 

The  comet  of  Pons  has  a  period  of 
71  years;  it  appeared  in  1812  and  re- 
turned to  us  in  1883,  and  is  due  again 
in  1954. 

Comets  frequently  have  more  than 
one  tail.  The  comet  of  1744  had  six 
tails,  which  spread  like  a  celestial  fan 
over  the  sky. 

Biela's  comet  was  discovered  by  him 
in  1827,  and  it  returned  regularly  in  its 
period  of  six  and  one-half  years.  On 
its  visit  in  1846  it  split  in  two  denned 
comets,  each  having  a  head,  coma,  and 
tail.  The  twin  comets  returned  "on 
time  "  in  1852,  but  have  never  appeared 


since ;  they  have  undoubtedly  been  lost, 
or  captured  by  the  attraction  of  some 
larger  body,  and  will  never  again  return 
to  the  sun. 

Halley's  comet  is  doubtless  the  most 
celebrated  of  all.  Since  the  year  12 
B.  c.  it  has  appeared  on  twenty-four  oc- 
casions ;  its  historical  visits  were  in  the 
year  1066,  when  William  the  Conqueror 
landed  in  England,  and  again  in  1456, 
after  the  capture  of  Constantinople  by 
the  Turks. 

On  many  of  its  visits  the  inhabitants 
of  Europe  were  terror-stricken  at  its 
appearance. 

It  has  a  period  of  T6  years,  and  its 
orbit  reaches  out  beyond  the  planet 
Neptune.  Halley  observed  it  on  its  vis- 
it in  1682,  and,  applying  the  principles 
of  Sir  Isaac  Newton,  he  identified  it  as 
the  comet  of  1066  and  1456.  Tracing  it 


64  THE    PITH   OF   ASTRONOMY 

back  to  12  B.C.,  and  fixing  its  period 
at  76  years,  he  staked  his  professional 
reputation  that  it  would  return  in  1758 
(after  his  death),  in  the  memorable  lines : 
"  Wherefore  if  it  should  return,  accord- 
ing to  my  prediction,  in  the  year  1758, 
impartial  posterity  will  not  refuse  to 
acknowledge  that  it  was  discovered  by 
an  Englishman."  It  appeared  on  Christ- 
inas day,  1758,  and  Halley  has  since 
held  a  niche  in  the  temple  of  fame. 

We  no  longer  regard  a  comet  as  a 
sign  of  impending  calamity.  We  now 
look  on  them  as  interesting  and  beauti- 
ful visitors,  which  come  to  please  and 
instruct  us,  but  never  to  threaten  or 
destroy. 


ASTEROIDS   OR  PLANETOIDS 

BETWEEN  the  orbits  of  Mars  and  Ju- 
piter there  is  a  space  of  nearly  400,000,- 
000  miles.  Up  to  the  year  1800  this 
belt  was  supposed  to  be  vacant.  On 
January  1,  1801,  Piazzi,  an  Italian  as- 
tronomer, discovered  the  minor  planet 
Ceres.  This  was  followed  by  an  embar- 
rassment of  riches,  and  to-day  more 
than  400  have  been  found. 

Ceres  is  the  largest.  Professor  Bar- 
nard gives  it  a  diameter  of  600  miles, 

Yesta  is  the  brightest,  as  it  can  be 
seen  by  the  naked  eye.  Its  diameter  is 
about  250  miles. 

Some  of  the  smaller  asteroids  run 


66  THE    PITH    OF   ASTKONOMY 

down  to  20  miles  in  diameter  and  even 
lower,  some  authorities  stating  that 
there  are  shoals  of  them  no  larger  than 
rocks. 

These  planets  revolve  round  the  sun 
(on  an  average)  in  less  than  five  years. 


SHOOTING-STARS 

THE  universe  swarms  with  meteoric 
stones.  These  bodies,  although  very 
small,  are  of  course  not  stationary, 
but  revolve  round  the  sun — that  is, 
those  that  come  within  the  domain  of 
the  solar  system.  They  are  governed 
by  the  same  laws  as  the'  other  bodies, 
and  are  a  part  of  our  system  —  a  part 
of  the  unity  of  the  universe.  They 
have  their  region  of  travel,  and  the  sun 
chains  them  and  the  giant  Jupiter  by 
the  same  po\ver  and  influence. 

When  they  come  near  enough  to  the 
earth  they  are  "  captured "  by  it,  and 
rush  into  our  atmosphere  with  such 


68  THE   PITH    OF   ASTRONOMY 

velocity  as  to  produce  a  degree  of  heat 
sufficient  to  vaporize  them  and  turn 
them  into  meteoric  dust.  During  this 
process  of  burning  they  appear  to  us  as 
shooting  stars. 

They  usually  become  luminous  about 
75  miles  from  the  surface  of  the  earth, 
and  are  entirely  consumed  by  friction 
before  they  descend  to  regions  where 
the  atmosphere  is  dense.  In  rare  in- 
stances they  are  so  large  that  they  are 
not  entirely  consumed,  but  fall  on  the 
earth  as  meteoric  stones  in  a  heated 
condition.  Specimens  of  them  may  be 
seen  at  most  of  our  museums.  These 
stones  encounter  the  earth  by  day  as 
well  as  by  night,  and  simultaneously  on 
all  parts  of  the  globe.  Professor  New- 
comb  has  demonstrated  that  one  hun- 
dred and  fifty  thousand  millions  of  them 
annually  fall  on  the  earth.  If  they  were 


SHOOTING-STARS  69 

not  melted  through  friction,  we  would  be 
subjected  to  a  continuous  bombardment, 
destructive  alike  to  our  lives  and  our 
property. 

Professor  Peirce  states  that  the  heat 
which  the  earth  receives  directly  from 
meteors  is  the  same  in  amount  which  it 
receives  from  the  sun  by  radiation,  and 
that  the  sun  receives  five-sixths  of  its  heat 
from  meteors  that  fall  on  it,  so  that,  after 
all,  these  little  stones  may  play  a  more 
important  part  in  our  personal  affairs 
than  we  give  them  credit  for. 

The  dust  caused  by  the  destruction 
of  these  stones  is  often  seen  on  the  arc- 
tic snows,  and  is  found  at  the  bottom  of 
the  oceans,  where  it  is  subjected  to  but 
little  agitation,  owing  to  the  compara- 
tive calm  prevailing  there.  The  writer 
has  seen  it  taken  from  the  bottom  of 
the  Indian  Ocean  by  lowering  a  hoi- 


70  THE   PITH    OF    ASTRONOMY 

low  socket  partially  filled  with  soft 
wax. 

There  are  two  thick  streams  of  these 
stones  that  are  annually  encountered  by 
the  earth  while  its  orbit  is  crossing 
theirs.  The  first  meeting  is  on  the 
night  of  August  10th ;  the  second  swarm 
is  encountered  on  November  14th,  at 
about  three  in  the  morning.  The  No- 
vember belt  is  thin,  and  the  earth  runs 
through  it  in  a  few  hours. 

The  August  stream  is  more  scattered, 
and  we  see  these  apparitions  for  some 
nights  both  before  and  after  the  10th, 
which  is  the  central  date  of  their  ap- 
pearance in  the  skies. 

There  have  been  many  remarkable 
star  showers  on  these  two  dates — the 
most  memorable  in  November,  1833; 
Olmsted,  the  astronomer,  estimated  that 
from  the  single  point  where  these  obser- 


SHOOTING-STARS  71 

vations  were  made  240,000  stars-  fell 
during  the  shower,  which  lasted  seven 
hours. 

Stone  showers  and  the  fall  of  large 
stones  have  been  more  or  less  frequent 
in  history. 

Several  thousands  of  stones  fell  in 
Hungary  on  June  9,  1866,  with  fright- 
ful noise ;  the  largest  fragment  weighed 
646  pounds. 

The  largest  authentic  aerolite  is  that 
found  at  Bendigo,  Brazil,  in  1816;  it 
weighs  five  and  a  half  tons;  it  was 
conveyed  to  Bio  Janeiro  in  1886. 

On  the  evening  of  December  21, 
1876,  a  meteor  of  unusual  size  and 
brilliancy  passed  over  the  states  of 
Kansas,  Missouri,  Illinois,  Indiana,  and 
Ohio.  It  was  first  seen  in  the  western 
part  of  Kansas,  at  an  altitude  of  sixty 
miles.  In  crossing  the  State  of  Mis- 


72  THE    PITH    OF    ASTRONOMY 

souri  it  commenced  to  explode,  and  this 
breaking  up  continued  while  passing 
over  Illinois,  Indiana,  and  Ohio,  till  it 
consisted  of  a  large  flock  of  brilliant 
balls  chasing  each  other  across  the  sky, 
the  number  being  variously  estimated 
at  from  50  to  100 ;  it  was  accompanied 
by  terrific  explosions,  and  was  seen 
along  a  path  of  not  less  than  1000  miles. 
The  writer's  recollection  of  the  occur- 
rence is  that  the  stones  were  lost  in 
Lake  Erie. 

While  writing  these  lines  the  news 
comes  through  the  Continental  papers 
that  one  of  the  greatest  meteorites 
ever  seen  recently  shot  across  Spain, 
coming  into  sight  over  the  Atlantic, 
and  falling  into  the  Mediterranean, 
or  perhaps  reaching  the  desert  of  Sa- 
hara, in  Africa.  On  the  morning  of 
February  10,  1896,  this  body  passed 


SHOOTING-STARS  73 

over  Madrid  with  deafening  explosions 
and  a  vivid  glare  of  blinding  light ;  it 
appeared  as  if  enveloped  in  a  bluish 
white  cloud  bordered  with  red;  the 
city  was  shaken  as  with  an  earthquake, 
many  windows  were  broken,  and  some 
light  structures  were  levelled  to  the 
ground ;  the  barometer  fell,  and  after- 
wards rose  rapidly.  Nearly  all  of  Spain 
was  treated  to  a  pyrotechnic  display; 
incandescent  fragments  fell  from  the 
flaming  meteor  at  Logrono  and  set  the 
town  on  fire  in  two  places. 

There  are  jinany  varieties  of  these 
bodies,  differing  in  size,  chemical  com- 
position, color,  and  origin  :  such  as  the 
ruins  of  vanished  worlds  scattered  into 
space,  the  debris  of  comets,  the  product 
of  volcanoes  on  stars  and  planets,  which 
may  include  bodies  projected  from  erup- 
tions on  our  own  earth  in  the  violent  vol- 


74  THE   PITH    OF    ASTRONOMY 

canic  disturbances  that  have  undoubt- 
edly taken  place  upon  it  in  prehistoric 
days ;  in  other  words,  they  represent  the 
accumulation  of  filings,  fragments,  and 
dust  from  the  celestial  workshop  in 
the  manufacture  and  disintegration  of 
worlds. 


THE  FIXED  STARS 

WE  have  finished  our  brief  notice  of 
the  solar  system  and  all  that  it  con- 
tains which  will  interest  the  casual 
reader,  and  must  therefore  now  cross 
the  "  Great  Divide  "  to  the  infinite  be- 
yond. 

What  does  crossing  this  divide  mean  ? 
It  means  that  we  must  leap  the  abyss 
from  Neptune,  our  solar  outpost,  to  the 
nearest  body  in  space,  the  fixed  star 
Alpha  Centauri,  some  twenty-five  thou- 
sand billions  of  miles  distant ;  then  an- 
other stride  of  nearly  twenty-five  thou- 
sand billions  more,  and  we  come  to  our 
second  neighbor,  the  star  61  Cygni. 


76  THE   PITH    OF   ASTRONOMY 

What  has  been  said  of  our  system 
will  not  more  than  represent  the  de- 
scription of  a  few  grains  of  sand  as 
compared  with  the  gigantic  machinery 
that  is  in  active  operation  beyond  the 
confines  and  influence  of  the  sun.  The 
fixed  stars  will  claim  our  first  atten- 
tion. 

All  the  stars  we  see  in  the  heavens 
are  popularly  called  "fixed  stars,"  to 
distinguish  them  from  the  wandering 
planets  of  the  solar  system.  The  name 
was  given  them  by  the  ancients,  when 
they  were  believed  to  be  stationary. 
Modern  science  has  shown  that  none  of 
them  are  "  fixed,"  but  that  every  one  of 
them  is  flying  through  the  universe  in 
some  direction,  with  a  velocity  that  is 
simply  incredible  to  those  who  have 
not  studied  the  subject. 

The  briefest  reflection  will  satisfy  any 


THE   FIXED   STARS  77 

intelligent  mind  that  the  laws  of  nature 
will  not  permit  any  body  to  hang  sus- 
pended in  space  without  motion ;  it 
must  move  or  fall  in  some  direction, 
and  when  it  falls  it  moves ;  so,  then,  it 
clearly  follows  that  all  is  motion  in  the 
heavens,  and  that  nothing  is  "fixed" 
or  stable.  AH  we  either  see  or  know 
of  fly,  fall,  roll,  or  rush  through  the  void, 
and  yet,  seen  as  a  whole,  all  seems  re- 
pose. But  it  is  not  so.  Each  sun  is 
moving  with  a  fearful  velocity. 

The  equilibrium  of  the  stars,  like  that 
of  our  planets,  is  maintained  by  the  ex- 
act balance  of  centrifugal  force  and  the 
attraction  of  gravitation ;  were  it  not 
for  the  balance  and  harmony  held  by 
these  forces  all  would  soon  be  turned 
to  chaos,  and  constant  collision  would 
destroy  the  worlds  in  existence.  The 
velocity  at  which  these  bodies  are  mov- 


78  THE    PITH   OF   ASTRONOMY 

ing  is  so  great  that,  were  they  to  meet, 
they  and  all  they  contain  would  be 
turned  into  vapor  in  less  than  a  second 
of  time. 

In  order  to  facilitate  the  indication 
of  the  size  and  brightness  of  a  star,  all 
the  stars  have  been  classed  in  the  order 
of  their  magnitude.  The  word  magni- 
tude, however,  is  misleading,  as  it  has 
no  connection  with  the  real  size  of  a 
star,  but  simply  indicates  how  they  ap- 
pear to  our  eyes.  Thousands  of  stars 
that  we  can  hardly  perceive  are  un- 
doubtedly giant  suns;  but,  owing  to 
their  immense  distance,  they  appear  to 
us  as  mere  specks  on  the  firmament. 
This  can  be  readily  illustrated  by  look- 
ing at  the  moon  and  Jupiter  in  our 
little  system ;  the  moon  is  but  a  mere 
fraction  of  Jupiter  in  reality,  but,  ow- 
ing to  the  difference  in  distance,  Jupi- 


THE   FIXED   STARS  79 

ter  appears  to  us  like  a  spark  of  light 
compared  with  the  size  of  our  satel- 
lite. 

Astronomers  have  agreed  on  19  stars 
of  the  first  magnitude ;  of  these,  6  are 
seen  in  the  southern  hemisphere,  leav- 
ing us  13  to  deal  with.  They  are  as  fol- 
lows, in  the  order  of  their  apparent 
size  and  brilliancy : 

Of  the  constellation 

Sirius, of  the  Great  Dog. 

Arcturus,    ....  of  the  Herdsman. 

Vega of  the  Lyre. 

Rigel, of  Orion. 

Capella, of  the  Wagoner. 

Procyon,     ....  of  the  Little  Dog. 

Betelguese,      ...  of  Orion. 

Aldebaran of  the  Bull. 

Antares of  the  Scorpion. 

Altair, of  the  Eagle. 

Spica, of  the  Virgin. 

Fomalhaut,      ...  of  Australia. 

Regulus, of  the  Lion. 


THE   PITH    OF   ASTRONOMY 

The  line  between  the  last  of  the  above 
list  and  the  first  stars  of  the  second  mag- 
nitude is  very  thin ;  many  would,  for 
instance,  include  the  second-magnitude 
stars  Castor  and  Pollux  within  the  lim- 
it of  the  first.  We  count  59  stars  of  the 
second  magnitude  and  128  of  the  third ; 
the  stars  in  the  succeeding  magnitudes 
run  into  the  thousands. 

Of  all  the  stars  there  are  but  23 
whose  distance  has  been  measured ;  the 
others  are  so  far  away  that  no  angle  or 
parallax  can  be  found  for  them  even  by 
observing  them  from  the  opposite  sides 
of  the  earth's  orbit,  which  in  itself  is 
about  200,000,000  miles  in  diameter. 

The  last  sun  in  this  list  that  has  been 
measured  is  the  catalogue  star,  1830 
Groombridge,  having  a  distance  of 
four  hundred  and  twenty-six  thousand 
billions  of  miles.  Of  the  distance  of  all 


THE   FIXED   STARS  81 

the  hosts  of  heaven,  with  the  above  ex- 
ceptions, we  know  nothing, 

Alpha  Centauri  is  the  nearest  sun ; 
it  is  twenty-live  thousand  billions  of 
miles  from  us.  It  would  take  an  ex- 
press train  73,000,000  years  to  reach  it 
from  the  earth. 

The  next  nearest  star  is  61  Cygni ; 
it  may  be  seen  in  the  constellation  of 
the  Swan  on  any  clear  night ;  it  is 
forty -nine  thousand  billions  of  miles 
from  this  planet. 

We  know  more  than  a  million  stars, 
separately  observed,  catalogued,  .and 
registered  on  celestial  charts,  but  the 
large  modern  telescope  can  now  reveal 
stars  of  the  fifteenth  magnitude,  and 
this  brings  hosts  of  new  suns  to  our 
knowledge,  estimated  to  be  at  least 
100,000,000  in  number. 

Celestial  photography  penetrates  still 


82  THE  PITH   OF   ASTRONOMY 

further  and  shows  more,  so  that  20,000 
stars  are  now  known  to  exist  for  every 
one  we  see  with  the  naked  eye. 

In  the  memory  of  man  many  stars 
have  changed ;  some  have  faded  from 
view,  others  have  become  brighter, 
while  a  few  have  changed  their  color, 
notably  Algol,  the  variable  star ;  it  was 
formerly  red,  but  is  now  white. 

All  the  stars  are  moving  in  one  di- 
rection or  another.  It  takes  Arcturus 
800  years  to  move  so  small  a  distance 
as  twice  the  apparent  diameter  of  the 
moon,  yet  it  is  moving  at  the  rate  of 
sixteen  hundred  millions  of  miles  year- 
ly ;  its  distance  is  so  great  it  does  not 
appear  to  move.  Another  example, 
Sirius,  takes  1300  years,  apparently,  to 
move  but  a  few  inches  in  the  sky,  yet 
its  minimum  speed  is  about  2,000,000 
miles  everv  dav. 


THE   FIXED   STARS  83 

It  was  not  always  safe  to  make  such 
assertions,  however,  as  Giordano  Bruno 
was  burned  alive  in  Rome  in  A.D.  1600, 
by  order  of  the  Inquisition,  for  asserting 
that  the  earth  was  not  standing  still 
and  was  not  the  centre  of  the  universe. 
Again  in  1616  and  1633,  Galileo,  one  of 
the  greatest  of  astronomers,  was  im- 
prisoned for  the  same  cause,  the  Pope 
ordering  that  all  books  should  be  de- 
stroyed that  asserted  the  motion  of  the 
earth. 

Some  stars  are  advancing  to  us,  others 
receding  at  great  velocity ;  but  their 
size  and  the  distance  is  so  enormous 
that  these  factors  count  but  little  in 
their  appearance  to  our  eyes.  Some  of 
the  larger  stars  fi}7ing  towards  us  are : 
the  Pole  Star,  at  the  rate  of  46  miles  a 
second ;  Vega,  at  44 ;  Arcturus,  at  50 ; 
and  Pollux,  at  40  miles ;  while  a  fe\v 


84  THE   PITH    OF   ASTRONOMY 

of  those  receding  are :  a  Coronae,  at  a 
speed  of  48  miles  a  second ;  Castor,  at  28 ; 
Capella,  at  27 ;  Kegulus,  at  23 ;  and  Sirius, 
the  Dog  Star,  at  22  miles  a  second. 

It  will  thus  be  seen  that  while  the 
twins  Castor  and  Pollux  have  stood 
side  by  side  in  the  heavens — at  least,  to 
human  eyes — for  4000  years,  yet  they 
are  flying  apart  at  the  velocity  of  68 
miles  a  second,  which  in  a  day  amounts 
to  over  5,000,000  miles.  This  for  40 
centuries,  and  still  they  are  "  the  twins  " 
to  our  eyes  to-day. 

The  student  of  stars  will  in  a  short 
time  begin  to  see  that  they  have  indi- 
vidual colors.  Many  of  these  are  clear- 
ly marked,  and  the  observer  will  at  once 
notice  their  various  tints.  It  is  believed 
they  take  their  colors  from  their  chem- 
ical composition  in  a  state  of  incandes- 
cence. 


THE    FIXED    STARS  85 

Aldebaran  and  Antares  are  red ;  Be- 
telguese  is  orange ;  Sirius,  Vega,  and 
Altair  are  bluish  white;  Arcturus, 
Capella,  and  Pollux  are  yellow;  while 
others  have  tints  of  the  r'uby>  the  emer- 
ald, the  topaz,  and  the  sapphire. 

There  are  many  variable  stars — that 
is,  stars  which  grow  bright  and  then 
fade  in  a  fixed  period.  Of  this  class 
Mira  and  Algol  are  the  most  remark- 
able.  Mira  attains  the  size  of  a  sec- 
ond-magnitude star  and  remains  in 
that  condition  15  days;  then  it  grad- 
ually fades  and  remains  invisible  for  5 
months;  afterwards  it  reappears  and 
increases  slowly,  to  again  become  brill- 
iant; the  entire  transformation  occu- 
pies 331  days.  Mira  is  sometimes  called 
"  the  wonderful." 

One  of  the  accepted  explanations  of 
these  changes  is  that  it  alternately 


86  THE   PITH    OF   ASTRONOMY 

burns  fiercely  and  smoulders  within  the 
time  of  its  period. 

Algol  has  a  short,  exact  period  of  2 
days,  20  hours,  and  48  minutes,  in  which 
it  makes  the  change  from  its  brightest 
to  its  faintest  condition.  It  has  kept 
time  to  these  figures  for  300  years. 
These  changes  are  caused  by  the  eclipse 
of  this  sun  by  an  enormous  dark  satel- 
lite. The  ancients  named  Algol  "  the 
demon." 

The  most  astonishing  change  comes 
from  the  southern  sky.  In  the  constel- 
lation of  Argo  the  star  known  as  Eta, 
in  1843,  disputed  with  Sirius  the  pre- 
miership of  the  skies.  In  1856  it  com- 
menced to  decrease,  and  gradually  be- 
came smaller,  till  at  length,  in  1870,  it 
left  our  sight.  Seen  at  present  with  a 
telescope  it  is  reviving,  and  may  in  the 
coming  century  regain  its  lost  glory. 


*  THE   FIXED   STABS  87 

If  this  sun  has  satellites  and  they  are 
inhabited,  all  their  living  beings  must 
have  perished  from  loss  of  heat. 

In  1572  Tycho  Brahe  observed  a  ne\v 
and  bright  star  that  suddenly  appeared 
in  the  constellation  of  Cassiopeia.  It 
was  so  bright  it  could  be  seen  in  day- 
light. It  gradually  faded  from  sight 
in  17  months,  and  has  never  been  seen 
since. 

The  causes  of  these  momentous 
changes  in  the  great  suns  of  space  are 
largely  a  matter  of  speculation.  There 
is  little  if  any  doubt  that  there  exists  a 
great  number  of  extinct,  burnt-out  suns 
— enormous  black  balls  that  gravitate 
round  other  dark  bodies  —  constituting 
dead  systems.  The  dying  throes  of 
these  monsters  may  have  taken  place  in 
a  celestial  conflagration  ending  in  their 
total  darkness. 


88  THE   PITH    OF   ASTEONOMY 

Another  theory  lately  advanced  by 
Professor  Lockyer  is  that  there  is  the 
closest  possible  connection  between  neb- 
ulas and  stars,  and  the  first  stage  in 
the  development  of  cosmical  bodies  is 
not  a  mass  of  hot  gas,  but  a  swarm  of 
cold  meteorites.  Many  bodies  in  space 
which  look  like  stars  are  really  centres 
of  nebulae — that  is,  of  meteoric  swarms — 
and  stars  with  bright  line  spectra  must 
be  associated  with  nebulae.  Some  of 
the  heavenly  bodies  are  increasing  their 
temperatures ;  others,  on  the  contrary, 
are  decreasing.  Double  swarms,  in  any 
stages  of  condensation,  may  give  rise 
to  the  phenomena  of  variability.  New 
stars  are  produced  by  the  clash  of  me- 
teor swarms,  and  are  closely  related  to 
nebulae  and  bright  line  stars.  Cosmical 
space  is  a  meteoric  plenum.  The  sun  is 
one  of  those  stars  the  temperature  of 


THE   FIXED   STARS  89 

which  is  rapidly  decreasing,  and  many 
of  its  changing  phenomena  are  due  to 
the  fall  of  meteoric  matter  upon  the 
photosphere. 

In  point  of  speed,  the  most  remarka- 
ble star  in  the  universe  is  the  seventh- 
magnitude  catalogue  star,  1830  Groom- 
bridge  ;  it  is  invisible  to  the  naked  eye, 
but  can  be  found  with  a  glass,  in  the 
Great  Bear.  Its  terrific  speed  is  such 
that  it  has  led  astronomers  to  believe 
it  is  not  propelled  by  any  force  we  know 
of,  but  by  some  power  from  another 
universe,  and  that  it  is  simply  a  vis- 
itor passing  through  our  skies.  It  is 
rushing  on  at  a  rate  of  17,000,000  miles 
daily. 

61  Cygni  comes  next  to  it  in  velocity. 
This  star  may  be  seen  with  the  naked 
eye  in  the  constellation  of  the  Swan; 
its  pace  is  over  100  miles  a  second. 


90  THE   PITH    OF   ASTRONOMY 

The  giants  Arcturus,  Yega,  and  Ca- 
pella  also  move  at  a  high  rate  of  speed. 

The  light  from  the  fixed  stars  is  a 
long  time  in  reaching  the  earth  ;  from 
the  very  nearest  it  is  about  four  years 
in  coming,  and  from  the  stars  that  are 
so  faint  that  we  can  hardly  see  them 
it  takes  many  thousands  of  years  to 
reach  us.  Good  authorities  estimate  it 
in  some  cases  as  long  as  100,000  years. 
At  the  rate  the  stars  are  moving  we, 
then,  never  really  see  them,  as  they  are 
billions  of  miles  away  from  the  point 
when  the  light  we  see  left  them.  It 
also  follows  that  succeeding  generations 
see  stars  that  have  become  extinct  for 
thousands  of  years. 

It  is  not  the  present  state  of  the  sky 
which  is  visible,  but  its  past  history. 

The  earth,  besides  rotating  on  its  axis 
and  revolving  round  the  sun,  reels  like 


THE   FIXED   STAKS  91 

a  mighty  gyroscope,  but  with  so  slow  a 
motion  that  it  takes  26,000  years  to 
make  one  complete  revolution  of  its 
axis  round  an  imaginary  line  perpen- 
dicular to  the  plane  in  which  the  earth 
moves.  Still  further :  as  this  axis  of  the 
earth  moves  in  its  circuit  round  this 
perpendicular  line  it  points  successively 
to  different  parts  of  the  heavens,  and  as 
the  point  in  the  heavens  to  which  the  axis 
is  directed  will  not  have  any  diurnal  mo- 
tion, all  the  stars  will  appear  to  revolve 
round  it,  or  round  the  star  that  may  be 
nearest  to  it;  from  which  circumstance 
it  will  be  called  the  Pole  Star. 

Polaris,  the  present  Pole  Star,  appears 
"  fixed  "  at  the  axis  of  the  earth,  but  in 
a  few  hundred  years  it  will  gradually 
commence  to  wear  away  from  it,  and 
in  about  the  year  9000  our  descendants 
will  elect  Alpha  Cygni  as  their  guide, 


92'  THE   PITH   OF   ASTRONOMY 

while  13,000  years  from  now  it  will  be 
the  beautiful  first-magnitude  star  Vega 
that  will  review  the  heavenly  host. 

Polaris  has  held  the  post  of  honor  for 
over  a  thousand  years,  and  was  pre- 
ceded in  office  by  Thuban,  of  the  Drag- 
on, to  see  which  in  daylight  the  long 
tunnel  in  the  Pyramid  of  Cheops  was 
built. 

The  writer  visited  an  observatory  in 
China  in  1874  said  to  be  4000  years  old, 
in  which  were  originally  placed  two 
bronze  eyeholes  on  a  slanting  granite 
wall  for  the  purpose  of  sighting  Thu- 
ban, the  Pole  Star  of  that  era.  In  1874 
the  line  of  sight  through  these  holes 
pointed  to  a  void,  all  the  stars  having 
moved  away  from  it. 


THE   CONSTELLATIONS 

"Orion's  beams!    Orion's  beams! 

His  star-gemm'd  belt,  and  shining  blade, 
His  iles  of  light,  his  silv'ry  streams, 
And  gloomy  gulfs  of  mystic  shade." 

FROM  the  very  earliest  ages  the  stars 
have  been  watched  with  interest  and 
admiration,  and  their  movements  traced 
and  applied  to  various  useful  purposes. 
In  those  days  "the  stars  in  their  courses" 
ruled  the  fate  of  men  and  nations. 

For  the  purpose  of  identifying  the 
stars  and  finding  out  more  about  them, 
the  first  watchers  of  the  sky  divided  the 
heavens  into  groups  or  constellations, 
naturally  naming  each  group  after  some 


94  THE  PITH    OF  ASTRONOMY 

object  to  which  they  fancied  it  had  a  re- 
semblance. As  the  first  observers  were 
chiefly  herdsmen,  we  can  readily  con- 
ceive how  some  of  the  oldest  constella- 
tions have  been  called  after  objects  and 
animals  with  which  the  shepherds  would 
be  familiar  in  those  early  times. 

Later  in  our  history  the  Greeks  set 
their  mythological  deities  in  the  skies, 
and  read  the  revolving  pictures  as  a 
starry  poem ;  they  colonized  the  earth 
widely,  but  the  heavens  completely,  and 
nightly  over  them  marched  the  grand 
procession  of  their  apotheosized  divini- 
ties. The  heavens  signify  much  more 
to  us,  but  we  retain  the  old  groupings 
and  pictures  for  our  convenience  in  find- 
ing individual  stars.  An  acquaintance 
with  the  names,  peculiarities,  and  move- 
ments of  the  stars  at  different  seasons 
of  the  year  is  an  unceasing  source  of 


THE  CONSTELLATIONS  95 

pleasure ;  one  can  never  be  alone  it  one 
is  familiarly  acquainted  with  the  stars. 

The  constellation  that  is  known  to 
almost  every  one — young  and  old — is 
the  Great  Bear,  popularly  known  as 
the  Dipper,  or  Plough.  The  reasons  for 
this  are  that  it  is  a  circumpolar  constel- 
lation—  consequently  it  is  always  in 
sight,  revolving  close  to  the  Pole  Star 
— and  that  it  has  a  remarkable  appear- 
ance, which  all  can  recognize. 

The  two  stars  on  the  edge  of  the 
Dipper  are  near  the  Pole  Star,  and  a 
line  drawn  through  them  points  to  it; 
they  are,  therefore,  called  the  "point- 
ers." This  constellation  contains  no 
stars  of  first  magnitude. 

The  group  known  as  Cassiopeia,  or 
Cassiopeia's  Chair,  is  a  companion  to 
the  Dipper,  and  is  always  opposite  to  it, 
as  both  swing  round  the  pole. 


96  THE   PITH   OF   ASTKONOMY 

The  grandest  constellation  is  the 
giant  Orion.  It  contains  seven  brill- 
iant stars,  two  of  them  of  the  first 
magnitude — viz.,  Betelguese  and  Rigel. 
Three  stars  lie  in  an  oblique  line  across 
the  middle  of  this  group,  and  are  known 
as  Orion's  Belt.  Flammarion  calls  this 
group  the  California  of  the  sky,  be- 
cause it  not  only  contains  the  above 
treasures,  but  in  the  middle  of  the  belt 
is  found  the  wonderful  nebula;  viewed 
through  a  powerful  telescope  there  are 
but  few  celestial  sights  that  cope  with 
it  in  weird  grandeur. 

Canis  Major,  or  the  Great  Dog,  ad- 
joins Orion,  and  is  remarkable  because 
it  contains  Sirius,  or  the  Dog  Star— - 
the  monarch  of  the  skies  and  the  great- 
est of  them  all  in  brilliancy  and  size. 

Bootes,  the  Herdsman,  contains  the 
giant  flying  sun  Arcturus,  which  looka 


THE   CONSTELLATIONS  97 

so  large  that  it  may  be  mistaken  for 
a  planet.  This  star  was  recorded  by 
Job  and  exploited  by  Homer.  It  is 
approaching  us  at  a  speed  of  50  miles 
a  second. 

Ursa  Minor,  or  the  Little  Bear,  is 
interesting  only  because  in  it  is  placed 
Polaris,  known  also  as  the  Pole  Star 
or  North  Star.  It  is  the  guide  of  the 
sailor  at  sea,  and  has  been  used  by  the 
slave  to  point  his  way  to  freedom.  It 
apparently  never  moves,  or  at  least  so 
little  that  its  motion  need  not  be  dis- 
cussed here. 

Taurus,  the  Bull,  claims  attention  be- 
cause it  contains  a  celebrated  group, 
the  Pleiades,  mentioned  by  Job,  and  the 
theme  of  poets  since  writing  began. 
The  ordinary  observer  can  see  six  stars 
in  this  group;  many  can  make  out 
seven;  but  Dawes,  the  keen -sighted 


98  THE   PITH    OF   ASTRONOMY 

Englishman,  counted  thirteen  under  fa- 
vorable circumstances.  A  recent  pho- 
tograph taken  in  Paris  shows  over  2000 
in  it.  Aldebaran,  the  great  red  sun,  is 
the  eye  of  the  bull,  and  may  be  easily 
located  on  account  of  its  marked  color. 
The  constellation  of  the  Lyre  is  not- 
ed because  of  Yega,  the  most  beautiful 
and  one  of  the  largest  stars  in  the  sky. 
It  may  be  recognized  by  the  formation 
of  a  small  equilateral  triangle  with  two 
minor  stars.  By  the  latest  decisions 
of  astronomers  the  solar  system  is  fly- 
ing towards  this  point.  Yega  can  al- 
ways be  seen  on  a  clear  night,  but  is 
more  brilliant  when  overhead  in  winter. 
This  is  true  of  all  stars  and  planets; 
when  they  are  on  the  horizon  we  have 
to  look  through  so  much  more  atmos- 
phere that  they  become  dim  to  our 
sight. 


THE    CONSTELLATIONS  99 

Leo,  the  Lion,  may  be  known  by  the 
exact  resemblance  it  now  bears  to  a 
sickle.  It  contains  Kegulus,  or  the 
Lion's  Heart,  as  well  as  Denebola.  It 
is  also  a  sign  of  the  zodiac. 

Aquila,  the  Eagle,  contains  the  brill- 
iant white  star  Altair,  having  small 
companions  close  to  it  on  each  side, 
the  three  making  a  straight  line. 

Cygnus,  the  Swan,  may  always  be 
found  in  the  Milky  Way ;  it  resembles 
a  large  cross  or  the  skeleton  of  a  kite 
more  than  it  does  a  swan. 

The  other  celebrated  constellations 
containing  first  -  magnitude  stars  are 
Auriga,  the  Wagoner,  containing  Ca- 
pella,  a  brilliant  yellow  star ;  the  Little 
Dog,  with  Procyon  within  its  limits  ; 
the  Scorpion,  with  the  red  star  Antares ; 
the  Yirgin,  containing  the  brilliant  sun 
Spica  as  its  feature.  There  are  about  a 


100  THE   PITH   OF   ASTRONOMY 

hundred  other  constellations,  but  they 
have  little  interest  for  those  not  mak- 
ing them  a  special  study,  and  are  com- 
paratively modern,  in  most  cases  being 
named  since  the  fourth  century. 

In  addition  to  the  constellations,  the 
entire  circumference  of  the  sky  has 
been  divided  into  twelve  parts,  which 
have  been  named  the  twelve  signs  of 
the  zodiac.  This  is  the  apparent  path 
of  the  sun  through  the  heavens.  Their 
names  and  order  may  be  easily  com- 
mitted to  memory  in  the  following 
rhyme : 

"The  Ram,  the  Bull,  the  Heavenly  Twins, 
And  next  the  Crab  the  Lion  shines, 

The  Virgin  and  the  Scales, 
The  Scorpion,  Archer,  and  Sea  Goat, 
The  man  that  holds  the  Watering-pot, 

And  Fish  with  glittering  tails." 

Some  of  these  signs  of  the  zodiac 


DEPARTMENT  OF  ASTRONOMY 

UNIVERSITY  OF  ^CALIFORNIA 

AT  LOS  ANGELES 

THE   CONSTELLATIONS  101 

ate  identical  with  the  great  constella- 
tions where  they  happen  to  lie  in  the 
sun's  course,  notably  the  Bull,  Lion, 
Virgin,  and  Scorpion;  the  other  eight 
zodiacal  signs  are  simply  minor  groups, 
made  memorable  because  they  are  the 
mile-posts  of  the  sun. 

It  was  explained  while  describing  the 
fixed  stars  that  in  reality  there  are  no 
"  fixed  "  stars ;  but  they  move  so  slowly 
to  our  eyes  that  the  ancients  believed 
them  to  be  stationary.  Their  proper  mo- 
tion, however,  causes  them  to  move,  and 
therefore  the  dislocation  of  the  heavens 
is  only  a  question  of  time.  The  day  will 
come  by  reason  of  this  motion  that  the 
neighboring  constellations  of  Orion,  the 
Bull,  and  Canis  Major  will  be  merged 
into  one  immense  group.  In  5000  years 
this  will  be  our  largest  and  grandest 
galaxy,  and  will  require  a  new  name. 


102  THE   PITH   OF   ASTRONOMY 

Such  a  period  seems  long  in  human  his- 
tory, but  it  is  but  an  hour  in  recording 
celestial  time,  when  we  consider  that 
most  astronomers  agree  in  placing  the 
age  of  our  little  modern  planet  at  20,- 
000,000  years. 

Astronomers  can  go  back  in  their  cal- 
culations with  as  remarkable  accuracy 
as  they  can  predict  the  future.  Fifty 
thousand  years  ago  the  Dipper  had  the 
form  of  a  perfect  cross,  and  in  500  cen- 
turies from  now  it  will  assume  the  shape 
of  a  steamer  chair. 


THK  GREAT  NKBULA  OF  ANDROMEDA 

(Visible  to  the  naked  eye.) 


NEBULA 

A  NEBULA  is  a  luminous  patch  in  the 
heavens,  billions  of  miles  beyond  the 
limits  of  our  solar  system. 

There  are  thousands  of  nebulae,  and 
they  are  of  various  composition,  color, 
and  size.  Sir  William  Herschel  observed 
and  formed  a  catalogue  numbering  2000 ; 
since  his  time  many  have  been  discov- 
ered by  the  aid  of  modern  telescopes. 
He  estimated  that  the  light  from  the 
faintest  would  take  2,000,000  years  to 
reach  us. 

Most  of  the  nebulae  proper  are  com- 
posed of  hydrogen  and  other  gases 
strongly  condensed ;  this  is  the  nucleus 


104  THE  PITH   OF  ASTRONOMY 

of  worlds  and  planets  in  the  process 
of  being  condensed  into  a  solid  mass. 
There  are  many  worlds  in  such  process 
of  evolution  known  to  astronomers,  and 
they  can  be  seen  in  their  different  stages 
through  a  telescope.  For  example,  one 
in  the  constellation  of  Canes  Venatici, 
which  shows  a  central  condensation, 
A  second  is  found  in  Aquarius,  and 
shows  a  sphere  in  the  process  of  throw- 
ing off  a  ring ;  this  ring  may  in  time 
condense  and  form  a  satellite.  A  third 
may  be  seen  in  Pegasus,  which  is  sur- 
rounded by  rings  of  gaseous  spirals. 
Two  of  the  most  celebrated  are  found 
in  the  constellations  of  Andromeda  and 
Orion ;  both  can  be  seen  on  a  clear  night 
by  the  naked  eye,  the  latter  surrounding 
the  middle  star  of  the  three  stars  in  Ori- 
on's sword.  This  is  the  celebrated  tra- 
pezium nebula — a  field  of  floating,  glow- 


THK  GREAT  NEBULA  ABOUT  THE  MULTIPLE  STAR  ORIONIS, 
IN  THE  CONSTELLATION  OF  ORION 


NEBULA  105 

ing  gas,  so  large  that  our  entire  solar 
system  would  be  lost  in  it.  It  is  one  of 
the  great  startling  sights  of  the  sky, 
and  those  who  are  privileged  to  see  it 
through  a  large  instrument  can  never 
forget  it. 

In  many  cases  these  nebulas  are  the 
graves  of  dead  worlds  and  the  cradles 
of  new  ones — immense  masses  of  un- 
organized matter  that  may  have  been 
left  floating  in  space — the  wreckage 
from  collisions  of  suns,  now  ready  to 
revert  back,  in  the  process  of  time,  to 
their  original  condition,  thus  sustaining 
the  trite  saying  that  nothing  is  lost  in 
nature. 


THE  MILKY  WAY 

THE  Galaxy,  or  Milky  Way,  is  a  lumi- 
nous band  of  irregular  form,  consisting 
of  a  great  circle  entirely  surrounding 
the  heavens.  It  contains  myriads  of 
stars,  so  crowded  together  that  their 
united  light  only  reaches  the  unaided 
eye ;  this  band  of  stars  can  be  seen  on 
any  dark,  clear  night.  If  we  could  stand 
where  the  earth  is  and  have  it  removed, 
we  could  see  this  splendid  circle  com- 
pletely surrounding  us ;  it  is  thus  rea- 
soned that  we  are  a  part  of  the  Milky 
Way,  and  that  our  sun  is  near  the  centre 
of  it. 

The  circumpolar  constellations  Gas- 


THE  CELEIWATED  CRAB  NEBULA  NEAR  TAUKI 


THE   MILKY    WAY  107 

siopeia  and  the  Swan  are  always  to  be 
found  in  the  Milky  Way,  while  Sirius, 
Capella,  and  Aquila  may  be  seen  on  its 
edge  when  they  are  in  sight. 

The  formation  of  the  Milky  Way  as- 
sumes the  general  appearance  of  a  sil- 
very ribbon,  but  in  places  it  is  divided 
into  two  great  branches,  which  after- 
wards reunite.  Between  these  divisions 
are  dark  places  comparatively  devoid  of 
stars ;  one  of  these,  the  Coal  Sack,  has 
become  celebrated,  and  was  so  named 
by  sailors  because  they  could  see  no 
stars  in  this  dark  spot. 

This  glorious  celestial  path  has  been 
the  theme  of  poets  in  all  ages.  Some  of 
the  best  lines  written  about  it  are  by 
Elizabeth  Carter,  from  which  the  follow- 
ing is  a  selection : 

"Throughout  the  Galaxy's  extended  line 
Unnumbered  orbs  in  gay  confusion  shine, 


108  THE    PITH    OF   ASTRONOMY 

Where  ev'ry  star  that  gilds  the  gloom  of  night 
With  the  faint  trembling  of  a  distant  light 
Perhaps  illumes  some  system  of  its  own 
With  the  strong  influence  of  a  radiant  sun." 


THK    NEBULA    IN    THE    MILKY    WAY 


DOUBLE  AND  MULTIPLE  STARS 

MANY  stars  that  appear  to  the  naked 
eye  as  a  single  object,  when  examined 
by  a  telescope  or  opera-glass  are  found 
to  be  composed  of  two,  three,  four,  or 
even  more  stars.  These  are  named 
double,  triple,  quadruple,  and  multiple 
stars.  Some  of  these  are  in  no  way 
connected  with  each  other  save  by  the 
accident  of  perspective,  while  in  many 
cases  they  Compose  a  system,  and  re- 
volve on  one  another  in  a  fixed  period ; 
the  periods  may  vary  from  a  few  years 
up  to  thousands. 

Ten  thousand  double  stars  have  been 
observed ;  the  great  majority  of  them 


110  THE   PITH   OF   ASTRONOMY 

are  really  double ;  by  the  chance  of  per- 
spective they  are  sometimes  located  al- 
most behind  each  other,  although  really 
billions  of  miles  apart. 

There  are  558  orbital  systems  known; 
23  ternary  systems  exist,  while  32 
triples  are  made  up  of  a  binary  system ; 
and  an  accidental  optical  companion, 
Kappa  Pegasi,  revolves  round  its  part- 
ner in  11  years,  which  is  the  shortest 
period  known. 

Zeta  Aquarii  has  the  longest  period 
definitely  fixed ;  it  is  1624  years. 

There  are  many  systems  whose  peri- 
ods exceed  5000  or  6000  years,  but 
enough  time  has  not  elapsed  since 
first  observed  to  exactly  fix  their  pe- 
riod. 

The  most  celebrated  double  stars  are 
Sirius  and  Castor,  of  the  Twins.  The 
former  has  a  period  of  53  years,  and  the 


DOUBLE   AND   MULTIPLE   STAKS         111 

latter  has  a  companion  that  revolves 
round  it  in  1001  years. 

The  ternary  system  of  Zeta,  in  the 
constellation  of  the  Crab,  is  composed 
of  three  suns;  the  second  revolves 
round  the  first  in  a  period  of  59  years, 
and  the  third  round  both  stars  in  600 
years. 

Double  stars  have  almost  always  dif- 
ferent colors,  and  frequently  exhibit  a 
brilliant  variety  of  tints.  Beta,  of  the 
Swan,  contains  two  suns,  one  being 
golden  yellow  and  the  other  sapphire. 
Antares  and  its  companion  are  orange 
and  green,  respectively. 

Procyon  is  so  perturbed  in  its  motion 
that  it  is  known  to  have  a  large  dark 
companion,  whose  attraction  affects  it, 
but  the  distance  is  so  immense  that  no 
observer  has  yet  been  able  to  find  the 
mysterious  partner. 


112  THE  PITH   OF   ASTRONOMY 

The  celebrated  star  61  Cygni  is  a 
telescopic  double  sun;  the  constituent 
parts  of  it  are  forty-five  times  as  far 
from  each  other  as  the  earth  is  from  the 
sun,  yet  it  takes  a  powerful  telescope  to 
show  any  distance  between  these  com- 
panions. No  better  illustration  of  the 
vast  scale  on  which  celestial  mechanics 
are  carried  on  can  be  found  than  by  re- 
flecting on  this  proposition. 

These  are  but  the  bare,  imperfect 
rudiments  of  astronomy,  and  represent 
but  a  taste  of  what  is  to  come  for  those 
who  wish  to  pursue  this  delightful  sci- 
ence in  its  details.  The  author  hopes 
that  this  little  effort  will  not  have  been 
made  in  vain ;  it  certainly  will  not  if  it 
induces  some  of  his  readers  to  take  up 
the  subject  in  earnest  where  he  has  laid 
down  his  pen. 


DOUBLE   AND   MULTIPLE   STABS         113 

"  What  though  no  real  voice  or  sound 
Amid  their  radiant  orbs  be  found  ? 
In  reason's  ear  they  all  rejoice, 
And  utter  forth  a  glorious  voice ; 
Forever  singing  as  they  shiue, 
'The  hand  that  made  us  is  divine.'" 


INTERESTING  ITEMS 

NICHOLAS  COPERNICUS.  Born  at  Thorn, 
Prussia,  A.D.  1473.  To  Copernicus  must 
be  given  the  first  place  in  astronomy, 
for  it  was  he  who,  in  the  face  of  all 
traditions,  founded  the  Copernican  sys- 
tem :  placing  the  sun  in  the  centre, 
with  the  planets  revolving  round  -it. 
Previous  to  1543  all  astronomers  placed 
the  earth  in  the  centre  of  the  universe, 
and  believed  that  the  stars  and  planets 
revolved  round  it. 

GALILEO. — Born  at  Pisa,  Italy,  1564. 
He  discovered  the  properties  of  the  pen- 
dulum in  1583,  constructed  a  thermome- 


YKKKKS    TKI.KSCOPK 
(In  the  possession  of  the  Chicago  University.    The 


INTERESTING    ITEMS  115 

ter  in  1597,  and  invented  and  construct- 
ed the  first  telescope  in  1609.  With 
these  appliances  he  made  many  impor- 
tant astronomical  discoveries. 

His  was  the  greatest  opportunity 
given  to  man  in  the  field  of  exploration, 
as  the  new  glass  placed  him  where  no 
one  had  stood  before ;  but  the  invention 
was  his,  and  he  used  it  to  the  fullest  ex- 
tent. He  was  imprisoned  in  Rome  for 
accepting  the  Copernican  system. 

SIE  ISAAC  NEWTON. — Born  in  England 
in  1642.  Newton  was  the  greatest 
mathematical  astronomer,  and  was  a 
veritable  wizard  with  figures,  distanc- 
ing all  men  who  had  lived  before  him 
or  who  have  appeared  since. 

The  story  of  the  fall  of  the  apple 
was  first  told  by  Voltaire,  who  obtained 
it  from  Newton's  niece.  Laying  down 


116  THE   PITH   OF   ASTRONOMY 

the  laws  of  universal  gravitation  was 
his  principal  work. 

Newton  was  a  philosopher  as  well  as 
a  great  astronomer,  as  the  treatment  of 
his  favorite  dog  will  show.  The  docu- 
ments completing  a  great  work  occu- 
pying forty  years  were  spread  on  his 
library  table ;  his  dog  upset  a  burning 
lamp  and  destroyed  them.  On  his  re- 
turn to  the  room  Newton  affectionately 
patted  the  dog  and  exclaimed,  "  Dia- 
mond, Diamond,  thou  little  knowest  the 
damage  thou  hast  done !" 

SIR  WILLIAM  HERSCHEL.  —  Born  in 
1738.  He  discovered  the  planet  Uranus 
and  many  other  celestial  bodies.  "With 
his  own  hands  he  constructed  the  first 
great  telescope.  It  has  been  said  of 
him  that  in  nearly  every  branch  of 
modern  physical  astronomy  he  was  the 


INTERESTING   ITEMS  117 

pioneer.  He  was  the  virtual  founder  of 
sidereal  science.  As  an  explorer  of  the 
heavens  he  had  but  one  rival — his  son. 

LIGHT  is  that  form  of  luminous  energy 
which  comes  to  the  eye  in  succeeding 
waves  or  vibrations  at  the  rate  of  four 
hundred  and  fifty  trillions  per  second. 
It  travels  at  the  rate  of  186,000  miles 
in  a  second,  and  this  uniform  speed  has 
had  much  to  do  in  settling  some  of  the 
greatest  astronomical  problems.  With- 
out its  aid  we  would  know  absolutely 
nothing  of  astronomy.  The  division  of 
light  from  the  sun  by  a  prism  results  in 
seven  colors,  in  the  following  order :  vio- 
let, indigo,  blue,  green,  yellow,  orange, 
and  red. 

This  is  known  as  the  solar  spectrum. 
The  most  extraordinary  phenomenon 
connected  with  light  and  at  present  en- 


118  THE   PITH    OF    ASTRONOMY 

tirely  unexplained  is  that  every  star  in 
the  sky  is  a  centre  of  constant  undula- 
tions in  all  directions,  which  thus  per- 
petually cross  each  other  through  space 
without  being  confused  or  mingled  in 
any  way. 

THE  SPECTROSCOPE. — This  wonderful 
instrument  makes  known  to  us  the  com- 
position of  celestial  bodies.  With  a 
system  of  prisms  it  divides  the  light 
from  them  into  lines  on  a  band  or  rib- 
bon. The  order  and  position  of  these 
lines  denote  the  chemical  composition 
of  the  body  under  examination,  so  that 
we  can  determine  exactly  all  the  sub- 
stances that  compose  it  and  their  per- 
centages. It  is,  in  fact,  the  autograph 
of  the  substance,  written  with  lines  in 
colors.  The  astronomer  by  its  aid  can 
as  easily  tell  what  the  sun  or  Sirius  are 


INTERESTING    ITEMS  119 

composed  of  as  a  chemist  can  analyze 
the  composition  of  gunpowder. 

No  LIGHT  WITHOUT  DUST. — The  major- 
ity do  not  know  that  the  sky  is  blue 
on  account  of  thousands  of  millions 
of  atoms  of  dust  floating  in  the  atmos- 
phere. Were  it  not  for  dust  we  would 
lack  light  on  earth  and  the  heavens 
would  be  an  inky  black. 

Suppose  a  room  absolutely  dark  save 
a  hole  through  one  of  the  shutters.  A 
ray  of  light  will  dart  through  the  small 
opening,  and  one  can  observe  tiny  par- 
ticles of  dust  dancing  in  that  bright 
beam  of  light.  As  a  matter  of  fact,  it  is 
not  "  the  light "  we  see,  but  simply  a  re- 
flection caused  by  these  motes  of  dust. 

As  it  is  with  this  shaft  of  light  in  the 
darkened  room,  so  it  is  on  a  large  scale 
throughout  the  air.  The  many  millions 


120  THE   PITH    OF   ASTRONOMY 

of  particles  of  dust  catch  the  light,  re- 
flecting it  back  and  forth  from  one 
to  another,  so  making  the  atmosphere 
luminous. 

Were  it  not  for  dust  the  sky  by  day 
would  appear  black,  as  it  does  at  night 
when  there  is  no  moon.  The  sun  would 
appear  as  an  immense  glowing  ball. 
The  moon  and  the  stars  would  be  visi- 
ble throughout  the  day.  Everything 
would  appear  differently.  Where  the 
light  touched,  the  eye  would  be  dazzled 
by  the  brilliancy.  The  mellow  softness 
of  the  shadows  would  become  an  in- 
tense black,  and  the  outlines  of  objects 
harsh  and  angular. 

The  sunlight,  which  has  been  ana- 
lyzed by  the  spectroscope,  consists  of  all 
the  colors  of  the  rainbow,  their  total 
forming  the  white  light.  The  white 
light  going  through  a  crystal  prism  is 


INTEKESTING    ITEMS  121 

broken  up  into  seven  component  parts, 
the  so-called  fundamental  colors.  These 
seven  distinct  colors  of  light  are  the 
result  of  the  different  lengths  of  ether 
waves.  Blue  is  one  of  the  shortest,  yel- 
low one  of  the  longest  waves.  Thus 
the  finest  dust  molecules  floating  high- 
est in  the  atmosphere  reflect  only  the 
blue  light,  imparting  that  tint  to  the 
heavens. 

TYCHO  BRAHE,  the  celebrated  Danish 
astronomer,  was  born  in  1546.  Fred- 
erick II.,  of  Denmark,  noticing  his  re- 
markable talents,  built  an  observatory 
for  him  on  the  island  of  Huen,  and  here 
it  was,  without  the  aid  of  a  telescope 
and  with  the  crudest  instruments,  he 
made  observations  that  afterwards  in 
the  hands  of  Newton  and  Kepler  were 
destined  to  settle  the  great  problems  of 


122  THE    PITH   OF   ASTRONOMY 

astronomy.  It  is  asserted  that  he  has 
never  been  surpassed  as  a  practical  as- 
tronomer, although  he  rejected  the  Co- 
pernican  theory.  He  was  eccentric  in 
his  conduct,  and  never  made  an  obser- 
vation in  his  observatory  without  put- 
ting on  his  court  dress,  alleging  that 
if  men  dressed  in  honor  of  the  king  and 
court  they  should  not  be  less  observant 
of  such  duties  in  the  presence  of  their 
Maker. 


THE    END 


POPULAR    ASTRONOMY 

By  SIMON  NEWCOMB,  LL.D.,  Superintendent 
American  Nautical  Almanac  ;  formerly  Profes- 
sor U.  S.  Naval  Observatory.  With  One  Hun- 
dred and  Twelve  Engravings,  and  Five  Maps 
of  the  Stars.  8vo,  Cloth,  $2  50;  School  Edi- 
tion, 12mo,  Cloth,  $1  30. 

Its  purpose  is  to  enlighten  that  great  mass  of  fairly  edu- 
cated people  who  have  lost  the  astronomical  knowledge 
that  they  once  possessed.  It  states  the  latest  methods  of 
investigation,  the  latest  discoveries,  and  the  latest  genera' 
development  of  this  majestic  and  almost  infinite  science. 
Great  thought  and  much  space  have  been  given  to  the  his- 
torical points  and  philosophical  aspects  of  the  science.  .  .  . 
In  the  treatment  of  weighty  and  abstruse  scientific  subjects, 
he  never  fails  to  bring  them  within  the  range  of  the  average 
popular  comprehension. — Boston  Pout. 

The  great  reputation  which  the  author  of  this  work  has 
merited  and  enjoys,  both  in  this  country  and  ill  Europe,  is 
a  sufficient  guarantee  of  its  excellence.  .  .  .  He  has  dwelt 
especially  upon  those  topics  which  have  just  now  a  popular 
and  philosophic  interest,  carefully  employing  such  language 
and  such  simple  explanations  as  will  be  intelligible  without 
laborious  study.  Technical  terms  have  as  much  as  possible 
been  avoided.  Such  as  were  employed  of  necessity,  and 
many  that  occur  elsewhere,  have  been  fully  explained  in  a 
copious  glossary  at  the  end  of  the  book.  With  its  abundant 
aid  the  reader  cannot  fail  to  derive  both  pleasure  and  en- 
tertainment froir  the  study  of  what  is  the  most  ancient  as 
well  as  the  most  elevating  and  inspiring  of  all  the  natural 
sciences.  .  .  .  Professor  Newcomb,  throughout  his  whole 
volume,  preserves  his  well-known  character  as  a  writer  who, 
in  treating  of  scientific  subjects,  fully  understands  the  art  i>f 
bringing  them  within  the  range  of  popular  comprehension. 
....  It  is  fully  calculated  to  hold  the  attention  of  the  gen- 
eral reader.— A'.  Y.  Times. 


PGBLISHED  BY  HARPER  &  BROTHERS,  NKW  YORK 

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RECREATIONS   IN  ASTRONOMY 

With  Directions  for  Practical  Experiments  and 
Telescopic  Work.  By  H.  W.  WARREN,  D.D. 
With  Eighty-three  Illustrations  and  Colored 
Plates.  12mo,  Cloth,  $1  25. 

Written  not  only  to  reveal  some  of  the  highest  achieve- 
ments of  the  human  mind,  but  also  to  let  the  heavens  de- 
clare the  glory  of  God.  With  sentiments  of  profound  devo- 
tion, and  with  the  calmest  belief  that  religion  gains  by 
every  advance  of  science,  he  invites  the  reader  to  scan  the 
heavens,  and  there  find  proofs  strong  as  holy  writ  of  the 
truths  of  revealed  faith.  Dr.  Warren  writes  like  a  scholar— 
clearly,  tersely,  elegantly.— Chicago  Times. 

The  style  of  the  author  is  flowing  and  easy,  so  that  even 
his  most  scientific  pages  will  make  the  reader  pause  and 
catch  the  drift  of  the  writing.  The  book  will  more  gener- 
ally interest  readers  that  most  books  upon  scientific  sub- 
jects. It  has  an  enthusiasm  which  is  contagious.  The 
author  has  mastered  well  the  art  of  bringing  science  into 
the  range  of  the  common  render  and  making  it  both  pleas- 
ant and  profitable— Chicago  Inter-Ocean. 

The  explanations  of  diflicult  matters  are  particularly  lucid, 
and  for  readers  not  technically  instructed  in  astronomy 
nothing  could  be  better  as  a  literary  presentation  of  the  at- 
tractive side  of  the  science.— N.  Y.  Evening  Post. 

A  very  attractive  book  .  .  .  treating  the  subject  in  so  fa- 
miliar a  manner  as  to  make  the  practical  and  useful  informa- 
tion it  contains  delightful  reading.— Boston  Commonwealth. 


PUBLISHED  BY  HARPER  &  BROTHERS,  NEW  YORK 

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Bayne  -  The  pith  of  astronomyewitbout 
mathematics a 

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DEPARTMENT  OF  ASTRONOMY 
UNIVERSITY  OF  CALIFORNIA 

UNIVERSITY  of 


